Conductive connecting pin and package substrate

ABSTRACT

A package substrate  310  incorporating a substrate provided with a conductor layer  5 , a conductive connecting pin  100  arranged to establish the electrical connection with a mother board and secured to the surface of the substrate, wherein a pad  16  for securing the conductive connecting pin is provided for the package substrate  310 . The pad  16  is covered with an organic resin insulating layer  15  having an opening  18  through which the pad  16  is partially exposed to the outside. The conductive connecting pin  100  is secured to the pad exposed to the outside through the opening with a conductive adhesive agent  17  so that solution of the conductive connecting pin  100  from the substrate occurring, for example when mounting is performed is prevented.

TECHNICAL FIELD

This application is a continuation of and claims the benefit of priorityunder 35 U.S.C. §120 from U.S. Ser. No. 09/830,949, filed Jul. 6, 2001,which is a National Stage of PCT/JP99/06428, filed Nov. 17, 1999, andclaims the benefit of priority under 35 U.S.C. §119 of JapaneseApplication Nos. 10-357039, filed Dec. 16, 1998; 11-034616, filed Jan.4, 1999; 11-097648, filed Apr. 5, 1999; 11-097649, filed Apr. 5, 1999;11-097650, filed Apr. 5, 1999; 11-104294, filed Apr. 12, 1999;11-231931, filed Aug. 18, 1999; 11-231932, filed Aug. 18, 1999;11-231933, filed Aug. 18, 1999; and 11-231934, filed Aug. 18, 1999. Thepresent invention relates to a conductive connecting pin and a resinpackage substrate to which the conductive connecting pin is secured.

BACKGROUND ART

In recent years, a package substrate for connecting IC chip or the liketo a mother board or a daughter board have been required to reduce itsdielectric constant and dielectric loss factor because the frequency ofeach signal has been raised. Therefore, the mainstream of the materialof the substrate has been changed from ceramics to resin.

In the foregoing background, as a technique relating to a printedcircuit board incorporating a resin substrate, a so-called build-upmultilayer printed board has been suggested in Japanese PatentPublication No. 4-55555. That is, epoxyacrylate is used to form an interlayer resin insulating layer on a glass epoxy substrate having formedcircuits. Then, a photolithographic method is employed to form anopening for a via hole. The surface is coarsened, and then a platingresist is provided to perform a plating process so that a conductivecircuit and the via hole are formed.

When the foregoing build-up multilayer printed circuit board is employedas a package substrate, a conductive connecting pin for establishing theconnection with a mother board or daughter board must be joined.

The foregoing pin is called a “T-type pin” having a T-like side shaperealized by a columnar connecting portion 722 and a plate-like securedportion 721 as shown in FIG. 76. Thus, the connecting portion 722 isused to establish the connection with a socket of mother board or thelike. The foregoing conductive pin 710 is, with a conductive adhesiveagent 717, such as solder, bonded and secured to a pad 716 which is aconductive layer of an inter layer resin insulating layer 752 (or a coresubstrate) which is the outermost layer of the build-up multilayercircuit plate.

The foregoing structure suffers from an excessively small area ofcontact between the pad 716 and the inter layer resin insulating layer752. Moreover, the metal pad and the resin insulating layer are made ofdifferent materials. Therefore, there arises a problem in that thestrength of adhesive bonding is unsatisfactorily small. Therefore, warpor asperities of the substrate sometimes occur owing to the differencein the coefficiency of thermal expansion between the package substrateand the mother board or the daughter board under a heat cycle conditionin which a high temperature and a low temperature are repeated and whichis performed as a reliability test. In the foregoing case, fracture ofthe interface occurs between the pad 716 and the inter layer resininsulating layer 752. Thus, there arises a problem in that theconductive connecting pin 720 separates from the substrate together withthe substrate. When the package substrate is mounted on the mother boardby using the conductive connecting pin, displacement between theposition of the conductive connecting pin and the socket of the motherboard causes stress to be concentrated to the connection portion. As aresult, the conductive connecting pin sometimes separates together withthe pad. Heat in the high temperature region in the heat cycle and thatgenerated when the IC chip is mounted, sometimes causes the conductivepin to be separated or inclined. Moreover, the electrical connectioncannot sometimes be established.

To solve the above-mentioned problems, an object of the presentinvention is to provide a conductive connecting pin which is free fromconcentration of stress under heat cycle conditions or during a mountingan electronic component such as an IC chip and a resin package substrateincorporating the conductive connecting pin which cannot easily bepeeled and separated and with which the electrical connection can easilybe established if the stress is exerted.

The build-up multilayer circuit plate for use as a package substrate hasa plane layer for constituting a power supply layer to permit supply oflarge electric power to the IC chip or a plane layer for constituting anearth layer to reduce noise.

However, the plane layer is connected to the pad which establishes theconnection with an external substrate (for example, a daughter board)through a via hole. The plane layer which constitutes the power supplylayer for the purpose of supplying electric current from the daughterboard portion through the fine via hole is able to supply only limitedelectric power to the IC chip. Therefore, a satisfactory function cannotbe realized. Also the plane layer, which constitutes the earth layer andwhich is connected to the earth line of the daughter board through thefine via hole having high resistance, cannot satisfactorily reducenoise.

To connect the multilayer printed circuit board for use as the packagesubstrate to the daughter board, the conductive connecting pin must bejoined to the pad provided for the multilayer printed circuit board. Ifa metal pad is provided for the package substrate made of resin, theconductive connecting pin separates together with the pad when stresshas been exerted on the conductive connecting pin because the strengthof adhesive bonding of each of the two elements is unsatisfactorily low.

To solve the above-mentioned problem, an object of the present inventionis to provide a package substrate incorporating a plane layer having asatisfactory function.

Another object of the present invention is to provide a resin packagesubstrate incorporating a plane layer having a satisfactory function anda conductive connecting pin which cannot easily be separated.

On the other hand, the build-up multilayer circuit plate incorporates aBGA constituted by solder or the like in order to establish theconnection with an external substrate. Thus, the build-up multilayercircuit plate is mounted on the surface of the external substrate.

When the connection with an external substrate is established throughthe BGA, too small area of adhesion between the BGA and the solderresist causes the tensile strength to be reduced. As a result,concentration of stress to the BGA or the heat cycle condition employedas the reliable test causes the BGA or a metal layer for holding the BGAto be cracked or broken.

A variety of heat hysteresis experienced with the build-up multilayercircuit board when it is formed, such as drying and hardening of theinter layer resin insulating layer and the solder resist (an organicresin insulating layer), drying occurring after a plated film has beenformed and an annealing process causes the substrate to be warped orasperities to occur. The warp and asperities sometimes inhibit theconnection between the build-up multilayer circuit plate and theexternal substrate by using the small BGA.

It might be considered feasible to establish the connection with theexternal substrate by using PGA as a substitute for the BGA of thebuild-up multilayer circuit plate. That is, the PGA establishes theelectrical connection by inserting a pin into a connection portion ofthe external substrate. Therefore, the foregoing defect in theconnection experienced with the BGA does not occur.

When the PGA is formed, through holes are formed in the substrate byusing a drill or a laser beam. Then, the PGA is inserted into thethrough hole. The build-up multilayer circuit plate incorporates theinsulating resin layer which does not contain a reinforcing agent madeof glass epoxy resin or the like. Therefore, the strength for supportingthe PGA is too small to enlarge the tensile strength. What is worse,plating solution which is used to form a conductive layer in the throughhole after the drilling operation has been performed, a variety of heathysteresis or heat required to melt solder in the through hole to securethe PGA sometimes causes the resin in the inter layer insulating layerto be melted. Thus, the PGA cannot sometimes be disposed.

Since the PGA requires the through hole to be formed, disposition of anelectric line in the lower layer is inhibited which is permitted for theBGA. Therefore, the degree of freedom required when the substrate isdesigned is narrowed excessively.

To solve the foregoing problems, an object of the present invention isto provide a package substrate with which the tensile strength of thePGA is enlarged and the degree of freedom of wiring can be widened andwhich exhibits a satisfactory connection characteristic with an externalsubstrate.

DISCLOSURE OF THE INVENTION

The inventors of the present invention have energetically performedstudies. As a result, the present invention has been established. Thatis, an aspect of the present invention claimed in claim 1 has astructure that a pad to which a conductive connecting pin is secured iscovered with an organic resin insulating layer having an opening forpartially exposing the pad. Therefore, for example, when the packagesubstrate is joined to another substrate, such as a mother board throughthe conductive connecting pin in a state where, for example, thepositions of the conductive connecting pin and the socket of the motherboard are sometimes deviated from each other. As an alternative to this,the heat hysteresis of the heat cycle condition sometimes causes thesubstrate to be warped. Even in the foregoing case, separation of thepad from the substrate, which is held by the organic resin insulatinglayer, can be prevented. If sufficiently large strength of adhesivebonding cannot be realized in a case of bonding different materials toeach other, such as bonding between a metal pad and an inter layer resininsulating layer, covering of the pad with the organic resin insulatinglayer realize large peel strength.

It is an important fact for the aspect claimed in claim 1 that the sizeof the pad is somewhat larger than the opening of the organic resininsulating layer through which the pad is exposed. Thus, the pad ispartially exposed to the outside through the foregoing opening. That is,the periphery of the pad is covered with the organic resin insulatinglayer. It is preferable that the size of the pad is 1.02 time to 100times the diameter of the opening of the organic resin insulating layerthrough which the pad is exposed to the outside. If the diameter of thepad is smaller than 1.02 of the diameter of the opening, the organicresin insulating layer cannot reliably hold the periphery of the pad.Therefore, separation of the conductive connecting pin cannot beprevented. If the size is larger than 100 times, raising of the densityof conductive layer is inhibited. Specifically, when the diameter of theopening formed in the organic resin insulating layer is 100 μm to 1,500μm, the diameter of the pad is 110 μm to 2,000 μm.

Another aspect of the present invention claimed in claim 2 has astructure that an extending portion over the periphery of the pad iscovered with an organic resin insulating layer. Therefore, if stress isapplied to the conductive connecting pin, separation from the substratecan be prevented because the pad is held by the organic resin insulatinglayer. On the other hand, the body of the pad is exposed to the outsidethrough the opening of the organic resin insulating layer. That is, theorganic resin insulating layer and the body of the pad are not incontact with each other. Therefore, the contact between the organicresin insulating layer and the body of the pad does not cause any crackto occur.

Another aspect of the present invention claimed in claim 5 has astructure that the pad is, through the via hole, joined to theconductive layer which is the inner layer. Therefore, the area ofcontact between the pad and the substrate is enlarged, causing the twoelements to be joined firmly. As described above, the aspect claimed inclaim 1 has the structure that the pad to which the conductiveconnecting pin is secured and the inter layer resin insulating layer towhich the pad is bonded are bonded to each other as bonding of differentmaterials. On the other hand, the aspect of the present inventionclaimed in claim 5 has the structure that the pad is connected to theconductive layer which is the inner layer. Therefore, the two elementsare connected to each other as the connection of metal elements.Therefore, the connection can furthermore reliably be established. Thepeeling strength of the pad can be enlarged.

The pad may be connected to the conductive layer, which is the innerlayer, through one or more via holes. The reason for this lies in thatthe area of contact of the pad can furthermore be enlarged toeffectively prevent the separation. When the pad is connected to theconductive layer, which is the inner layer, through the via hole, it iseffective that the via hole is formed in the periphery of the pad.Therefore, the via hole may be formed into a ring shape and the pad maybe disposed to cover the ring.

The pad to which the conductive connecting pin of the build-upmultilayer circuit plate is connected may be so structured as to beconnected to the conductive layer, which is the inner layer, through twoor more layers of via holes. The two or more layers of the via holes maybe one via hole according to the shape or the type of the packagesubstrate. In either case, the surface area of the pad can be enlargedto effectively enlarge the strength of adhesive bonding. When the viahole provided with the pad is covered with the organic resin insulatinglayer having the opening through which the pad is partially exposed tothe outside, separation of the pad can reliably be prevented.

Another aspect of the present invention claimed in claim 6 has astructure that the conductive layer of the core substrate is made firmlycontact with the surface of a resin substrate serving as a coresubstrate through a coarsened surface (a mat surface). When a pad isconnected to the foregoing conductive layer, the pad cannot easily beseparated from the inter layer resin insulating layer. Also in a casewhere the pad is joined to the conductive layer, which is the innerlayer, through one or more via holes and two or more layers of viaholes, the conductive layer, which is the inner layer, may be providedfor the core substrate.

According to another aspect of the present invention claimed in claim 7is able to elongate the length of the electric wire from the conductiveconnecting pin, which is an external terminal, to another substratedisposed on a side surface opposite to the side surface for which theconductive connecting pin is prevented. Specifically, the pad isconnected to the land around the through hole and a filer filled in thethrough hole through a via hole. Moreover, so-called “cover plating” maybe performed such that the through hole is covered with a conductivelayer. Then, the pad may be connected to the conductive layer throughthe via hole. Moreover, the pad may be connected to only the land of thethrough hole through the via hole.

According to another aspect of the present invention claimed in claim 14has a structure that the strength of adhesive bonding with theconductive connecting pin can be made to be 2.0 Kg/pin or greaterbecause the melting point of the conductive adhesive agent is 180° C. to280° C. The foregoing strength is not considerably reduced even afterthe reliability test, such as a heat cycle test, or even after heat hasbeen applied during mounting of IC chips. If the melting point is lowerthan 180° C., realized strength of adhesive bonding is about 2.0 Kg/pin.In some cases, only unsatisfactory strength of adhesive bonding of 1.5Kg/pin can be realized. What is worse, heating applied during mountingof the IC chips sometimes causes the conductive adhesive agent to bemelted. Thus, the conductive connecting pin is undesirably separated andinclined. If the melting point is higher than 280° C., the resininsulating which is the resin layer and the solder resist layer areunsatisfactory dissolved at a temperature at which the conductiveadhesive agent is dissolved. It is preferable that the temperature is200° C. to 260° C. When the conductive adhesive agent has theabove-mentioned melting point, dispersion of the strength of adhesivebonding of the conductive connecting pin can be reduced. Moreover,applied heat does not damage the resin layer which constitutes thepackage substrate.

Another aspect of the present invention claimed in claim 15 has astructure that the conductive adhesive agent is made of at least onetype of material selected from tin, lead, antimony, silver, gold andcopper. Therefore, the conductive adhesive agent having theabove-mentioned melting point can be prepared. In particular, aconductive adhesive agent containing at least tin-lead or tin-antimonyis able to realize the above-mentioned range of the melting point. Ifthe conductive adhesive agent is melted, re-fixation easily occurs.Thus, separation and inclination of the conductive connecting pin do notoccur.

When the conductive adhesive agent is made of an alloy, such as Sn/Pb,Sn/Sb, Sn/Ag or Sn/Sb/Pb, the strength of adhesive bonding can be madeto be 2.0 Kg/pin. Moreover, dispersion of the strength of adhesivebonding can be restrained. Even with the heat cycle condition and heatapplied during mounting of IC chips, reduction in the strength ofadhesive bonding of the conductive connecting pin can be prevented.Moreover, separation and inclination of the pin can be prevented. Inaddition, also electrical connection can also be maintained.

Another aspect of the present invention claimed in claim 17 has astructure that the conductive connecting pin is made of at least onetype of metal materials selected from copper, a copper alloy, tin, zinc,aluminum and noble metal having excellent flexibility. Therefore, whenstress is applied to the pin, the pin is deflected so that the stress isabsorbed. As a result, the conductive connecting pin cannot easily beseparated from the substrate. It is preferable that the copper alloy forconstituting the conductive connecting pin is phosphor bronze whichexhibits excellent flexibility and satisfactory electric characteristicsand which permits easy processing of the conductive connecting pin.

It is preferable that the conductive connecting pin is a so-calledT-type pin incorporating a plate-like secured portion and a columnarconnection portion projecting over the central portion of the plate-likesecured portion. The plate-like secured portion is a portion which is,through the conductive adhesive agent, secured to the conductive layerwhich is formed into the pad. The foregoing plate-like secured portionis formed into an arbitrary shape including a circular shape and apolygonal shape adaptable to the size of the pad. The shape of theconnection portion is required to permit insertion into anothersubstrate. The shape may be any one of a cylindrical shape, a prismaticshape, a conical shape and a pyramid shape. Usually, one pin is providedfor the pin disposed at a usual position. Two or more connectionportions may be provided. The number of the connection portions mayarbitrarily be determined.

It is preferable that the columnar connection portion of the conductiveconnecting pin has a diameter of 0.1 mm to 0.8 mm, the length of 1.0 mmto 10 mm and the diameter of the columnar secured portion is 0.5 mm to2.0 mm. The foregoing values are arbitrarily determined according to thesize of the pad and the type or the like of another substrate which mustbe mounted.

Another aspect of the present invention claimed in claim 19 is able toabsorb stress because the connection portion is deflected if the stressis applied to the conductive connecting pin because the positions of theconductive connecting pin and the other substrate are deviated from eachother. If warp of the substrate or the like occurs owing to heathysteresis of the heat cycle condition, the secured portion is deflectedto correspond to the deformation. Therefore, separation of theconductive connecting pin from the substrate can be prevented. As aresult, a reliable package substrate can be obtained.

The package substrate according to claim 19 may have a structure that apad, to which the conductive connecting pin is connected, is coveredwith an organic resin insulating layer having an opening through whichthe pad is partially exposed. As a result, if concentration of stress tothe conductive connecting pin or deformation of the substrate takesplace as described above, the structure that the pad is pressed by theorganic resin insulating layer is able to prevent separation of the padfrom the substrate, can be prevented. If sufficiently large strength ofadhesive bonding cannot easily be obtained in a case of bonding ofdifferent materials to each other, such as the metal pad and the interlayer resin insulating layer, covering of the surface of the pad withthe organic resin insulating layer permits great peeling strength to beobtained.

When the pad is covered with the organic resin insulating layer, it isan important fact that the size of the pad is somewhat larger than thatof the opening formed in the organic resin insulating layer throughwhich the pad is exposed to the outside. As a result, the pad canpartially be exposed to the outside through the opening. That is, theperiphery can be covered with the organic resin insulating layer. It ispreferable that the size of the pad is such that the diameter of the padis 1.02 time to 100 times the diameter of the opening of the organicresin insulating layer through which the pad is exposed to the outside.If the diameter of the pad is smaller than 1.02 time the diameter of theopening, the periphery of the pad cannot reliably be held by the organicresin insulating layer. Therefore, separation of the conductiveconnecting pin cannot be prevented. If the diameter is larger than 100times, raising of the density of the conductive layer is inhibited.Specifically, when the diameter of the opening formed in the organicresin insulating layer is 100 μm to 1,500 μm, the diameter of the pad is110 μm to 2,000 μm.

Another aspect of the present invention claimed in claim 23 has astructure that the conductive connecting pin is made of at least onetype of metal selected from copper, a copper alloy, tin, zinc, aluminumand noble metal, exhibiting excellent flexibility. Moreover, the pad forsecuring the conductive connecting pin is joined to a conductive layer,which is the inner layer, through the via hole. In addition to theeffect that stress is absorbed owing to easy deflection of theconductive connecting pin, the area of contact between the pad and thesubstrate can be enlarged so that the two elements are firmly joined toeach other. As described above, the aspect claimed in claim 19 has thestructure that the pad, to which the conductive connecting pin issecured, and the inter layer resin insulating layer to which the pad isbonded are bonded to each other such that different materials are bondedto each other. On the other hand, the aspect claimed in this claim hasthe structure that the pad is connected to the conductive layer which isthe inner layer. Therefore, the two elements are connected to each otheras the connection between metal elements. Thus, hermetic contact canfurthermore reliably be established and the peeling strength of the padcan be enlarged.

The pad may be connected to the conductive layer, which is the innerlayer, through one or more via holes. The reason for this lies in thatthe area of contact of the pad can furthermore be enlarged. Thus, astructure with which peeling does not easily occur can be realized. Whenthe pad is connected to the conductive layer, which is the inner layer,through the via hole, it is effective that the via hole is disposed inthe periphery of the pad from a viewpoint of improving the connectioncharacteristic. Therefore, a structure may be formed such that the viahole is formed into a ring shape and the pad is disposed to cover thering.

The pad of the build-up multilayer circuit plate to which the conductiveconnecting pin is secured may be so structured as to be connected to theconductive layer, which is the inner layer, through two or more layersof the via holes. According to the shape and type of the packagesubstrate, the two or more layers of the via holes may be constituted byone or more via holes. In either case, the surface area of the pad canbe enlarged to effectively enlarge the strength of adhesive bonding.When the via hole provided with the pad is covered with the organicresin insulating layer having the opening through which the pad ispartially exposed to the outside, separation of the pad can reliably beprevented.

Another aspect of the present invention claimed in claim 24 has astructure that the conductive layer on the core substrate is made tohermetically contact with the surface of the resin substrate through thecoarsened surface (the mat surface). When the pad is connected to theforegoing conductive layer, separation of the pad from the inter layerresin insulating layer can furthermore reliably be prevented. Also in acase where the pad is joined to the conductive layer, which is the innerlayer, through one or more via holes or two or more layers of the viaholes, the conductive layer, which is the inner layer, may be providedfor the core substrate.

Another aspect of the present invention claimed in claim 25 is able toshorten the length of the electric wire from the conductive connectingpin to another substrate disposed on the side surface opposite to theside surface provided with the conductive connecting pin. Specifically,the pad is connected to the land around the through hole and a filerfilled in the through hole through a via hole. Moreover, so-called“cover plating” may be performed such that the through hole is coveredwith a conductive layer. Then, the pad may be connected to theconductive layer through the via hole. Moreover, the pad may beconnected to only the land of the through hole through the via hole.

Another aspect of the present invention claimed in claim 32 has astructure that the strength of adhesive bonding with the conductiveconnecting pin can be made to be 2.0 Kg/pin or greater because themelting point of the conductive adhesive agent is 180° C. to 280° C. Theforegoing strength is not considerably reduced even after thereliability test, such as a heat cycle test, or even after heat has beenapplied during mounting of IC chips. If the melting point is lower than180° C., realized strength of adhesive bonding is about 2.0 Kg/pin. Insome cases, only unsatisfactory strength of adhesive bonding of 1.5Kg/pin can be realized. What is worse, heating applied during mountingof the IC chips sometimes causes the conductive adhesive agent to bemelted. Thus, the conductive connecting pin is undesirably separated andinclined. If the melting point is higher than 280° C., the resininsulating which is the resin layer and the solder resist layer areunsatisfactorily dissolved at a temperature at which the conductiveadhesive agent is dissolved. It is preferable that the temperature is200° C. to 260° C. When the conductive adhesive agent has theabove-mentioned melting point, dispersion of the strength of adhesivebonding of the conductive connecting pin can be reduced. Moreover,applied heat does not damage the resin layer which constitutes thepackage substrate.

Another aspect of the present invention claimed in claim 33 has astructure that the conductive adhesive agent is made of at least onetype of material selected from tin, lead, antimony, silver, gold andcopper. Therefore, the conductive adhesive agent having theabove-mentioned melting point can be prepared. In particular, aconductive adhesive agent containing at least tin-lead or tin-antimonyis able to realize the above-mentioned range of the melting point. Ifthe conductive adhesive agent is melted, re-fixation easily occurs.Thus, separation and inclination of the conductive connecting pin do notoccur.

When the conductive adhesive agent is made of an alloy, such as Sn/Pb,Sn/Sb, Sn/Ag or Sn/Sb/Pb, the strength of adhesive bonding can be madeto be 2.0 Kg/pin. Moreover, dispersion of the strength of adhesivebonding can be restrained. Even with the heat cycle condition and heatapplied during mounting of IC chips, reduction in the strength ofadhesive bonding of the conductive connecting pin can be prevented.Moreover, separation and inclination of the pin can be prevented. Inaddition, also electrical connection can be maintained.

Another aspect of the present invention claimed in claim 35 has astructure that the columnar connection portion of the conductiveconnecting pin has a constriction portion having a diameter smaller thanthat of the other portions. Therefore, flexibility is imparted to thepin. Therefore, if stress is applied to the conductive connecting pin,the connection portion is bent at the constriction portion. Therefore,stress can be absorbed so that easy separation of the conductiveconnecting pin from the substrate is prevented.

It is preferable that the conductive connecting pin is a so-calledT-type pin incorporating a plate-like secured portion and a columnarconnection portion projecting over the central portion of the plate-likesecured portion.

The plate-like secured portion is a portion which is, through theconductive adhesive agent, secured to the conductive layer which isformed into the pad. The foregoing plate-like secured portion is formedinto an arbitrary shape including a circular shape and a polygonal shapeadaptable to the size of the pad. The shape of the connection portion isrequired to permit insertion into another substrate. The shape may beany one of a cylindrical shape, a prismatic shape, a conical shape and apyramid shape. Usually, one pin is provided for the pin disposed at ausual position. Two or more connection portions may be provided. Thenumber of the connection portions may arbitrarily be determined.

It is preferable that the conductive connecting pin is structured suchthat the diameter of the plate-like secured portion is 0.5 mm to 2.0 mm,the diameter of the columnar connection portion is 0.1 mm to 0.8 mm andthe length is 1 mm to 10 mm. The foregoing values are arbitrarilydetermined according to the size of the package substrate which must besecured and the type or the like of another substrate which must bemounted.

The constriction portion is formed at an intermediate position of theconnection portion such that the diameter of the constriction portion issmaller than the diameter of the other portions. The diameter of theconstriction portion varies according to the material of the conductiveconnecting pin and the size of the conductive connecting pin. It is animportant fact that the foregoing diameter is not less than 50% nor morethan 98% of the diameter of the connection portion. If the diameter ofthe constriction portion is smaller than 50% of the diameter of theother portions, the strength of the connection portion isunsatisfactory. When the package substrate has been joined, deformationand breakage sometimes occur. If the diameter of the constrictionportion is larger than 98% of the other portion, predeterminedflexibility cannot be imparted to the connection portion. Therefore, theeffect of absorbing stress cannot be obtained. A plurality of theconstriction portions may be formed (see FIG. 33 (B)).

The material of the conductive connecting pin according to the presentinvention is not limited if the material is a metal material. It ispreferable that at least any one of metal materials, such as gold,silver, copper, nickel, cobalt, tin and lead is employed to form theconductive connecting pin. Any one of an iron alloy having trade name“COBAL” (an alloy of Ni—Co—Fe), stainless steel and a phosphor bronzewhich is a copper alloy is a preferred material because of an externalelectrical characteristic and satisfactory processability of theconductive connecting pin. Phosphor bronze having external flexibilityis able to satisfactorily absorb stress.

Another aspect of the present invention claimed in claim 37 is able toabsorb stress because the connection portion is deflected if the stressis applied to the conductive connecting pin because the positions of theconductive connecting pin and the other substrate are deviated from eachother. If warp of the substrate or the like occurs owing to heathysteresis of the heat cycle condition, the secured portion is deflectedto correspond to the deformation. Therefore, separation of theconductive connecting pin from the substrate can be prevented. As aresult, a reliable package substrate can be obtained.

The package substrate according to claim 37 may have a structure that apad, to which the conductive connecting pin is connected, is coveredwith an organic resin insulating layer having an opening through whichthe pad is partially exposed. As a result, if concentration of stress tothe conductive connecting pin or deformation of the substrate takesplace as described above, the structure that the pad is pressed by theorganic resin insulating layer is able to prevent separation of the padfrom the substrate, can be prevented. If sufficiently large strength ofadhesive bonding cannot easily be obtained in a case of bonding ofdifferent materials to each other, such as the metal pad and the interlayer resin insulating layer, covering of the surface of the pad withthe organic resin insulating layer permits great peeling strength to beobtained.

When the pad is covered with the organic resin insulating layer, it isan important fact that the size of the pad is somewhat larger than thatof the opening formed in the organic resin insulating layer throughwhich the pad is exposed to the outside. As a result, the pad canpartially be exposed to the outside through the opening. That is, theperiphery can be covered with the organic resin insulating layer. It ispreferable that the size of the pad is such that the diameter of the padis 1.02 time to 100 times the diameter of the opening of the organicresin insulating layer through which the pad is exposed to the outside.If the diameter of the pad is smaller than 1.02 time the diameter of theopening, the periphery of the pad cannot reliably be held by the organicresin insulating layer. Therefore, separation of the conductiveconnecting pin cannot be prevented. If the diameter is larger than 100times, raising of the density of the conductive layer is inhibited.Specifically, when the diameter of the opening formed in the organicresin insulating layer is 100 μm to 1,500 μm, the diameter of the pad is110 μm to 2,000 νm.

Another aspect of the present invention claimed in claim 41 has astructure that the connection portion of the conductive connecting pinhas a constriction portion to obtain flexibility. Moreover, the pad forsecuring the conductive connecting pin is joined to the conductivelayer, which is the inner layer, through the via hole. Therefore, thearea of contact between the pad and the substrate can be enlarged tofirmly join the two elements. As described above, the aspect claimedclaim 37 has the structure that the pad, to which the conductiveconnecting pin is secured, and the inter layer resin insulating layer towhich the pad has been bonded are bonded to each other as bondingbetween different materials. This aspect has the structure that the padis connected to the conductive layer which is the inner layer.Therefore, the two elements can reliably be made to contact hermeticallywith each other because metal elements are connected to each other.Therefore, the peeling strength of the pad can be enlarged.

The pad may be connected to the conductive layer, which is the innerlayer, through one or more via holes. The reason for this lies in thatthe area of contact of the pad can furthermore be enlarged toeffectively prevent the separation. When the pad is connected to theconductive layer, which is the inner layer, through the via hole, it iseffective that the via hole is formed in the periphery of the pad.Therefore, the via hole may be formed into a ring shape and the pad maybe disposed to cover the ring.

The pad to which the conductive connecting pin of the build-upmultilayer circuit plate is connected may be so structured as to beconnected to the conductive layer, which is the inner layer, through twoor more layers of via holes. The two or more layers of the via holes maybe one via hole according to the shape or the type of the packagesubstrate. In either case, the surface area of the pad can be enlargedto effectively enlarge the strength of adhesive bonding. When the viahole provided with the pad is covered with the organic resin insulatinglayer having the opening through which the pad is partially exposed tothe outside, separation of the pad can reliably be prevented.

Another aspect of the present invention claimed in claim 42 has astructure that the conductive layer of the core substrate is made tofirmly contact with the surface of a resin substrate serving as a coresubstrate through a coarsened surface (a mat surface). When a pad isconnected to the foregoing conductive layer, the pad cannot easily beseparated from the inter layer resin insulating layer. Also in a casewhere the pad is joined to the conductive layer, which is the innerlayer, through one or more via holes and two or more layers of viaholes, the conductive layer, which is the inner layer, may be providedfor the core substrate.

According to another aspect of the present invention claimed in claim43, it is able to elongate the length of the electric wire from theconductive connecting pin, which is an external terminal, to anothersubstrate disposed on a side surface opposite to the side surface forwhich the conductive connecting pin is prevented. Specifically, the padis connected to the land around the through hole and a filer filled inthe through hole through a via hole. Moreover, so-called “cover plating”may be performed such that the through hole is covered with a conductivelayer. Then, the pad may be connected to the conductive layer throughthe via hole. Moreover, the pad may be connected to only the land of thethrough hole through the via hole.

According to another aspect of the present invention claimed in claim 50has a structure that the strength of adhesive bonding with theconductive connecting pin can be made to be 2.0 Kg/pin or greaterbecause the melting point of the conductive adhesive agent is 180° C. to280° C. The foregoing strength is not considerably reduced even afterthe reliability test, such as a heat cycle test, or even after heat hasbeen applied during mounting of IC chips. If the melting point is lowerthan 180° C., realized strength of adhesive bonding is about 2.0 Kg/pin.In some cases, only unsatisfactory strength of adhesive bonding of 1.5Kg/pin can be realized. What is worse, heating applied during mountingof the IC chips sometimes causes the conductive adhesive agent to bemelted. Thus, the conductive connecting pin is undesirably separated andinclined. If the melting point is higher than 280° C., the resininsulating which is the resin layer and the solder resist layer areunsatisfactorily dissolved at a temperature at which the conductiveadhesive agent is dissolved. It is preferable that the temperature is200° C. to 260° C. When the conductive adhesive agent has theabove-mentioned melting point, dispersion of the strength of adhesivebonding of the conductive connecting pin can be reduced. Moreover,applied heat does not damage the resin layer which constitutes thepackage substrate.

Another aspect of the present invention claimed in claim 51 has astructure that the conductive adhesive agent is made of at least onetype of material selected from tin, lead, antimony, silver, gold andcopper. Therefore, the conductive adhesive agent having theabove-mentioned melting point can be prepared. In particular, aconductive adhesive agent containing at least tin-lead or tin-antimonyis able to realize the above-mentioned range of the melting point. Ifthe conductive adhesive agent is melted, re-fixation easily occurs.Thus, separation and inclination of the conductive connecting pin do notoccur.

When the conductive adhesive agent is made of an alloy, such as Sn/Pb,Sn/Sb, Sn/Ag or Sn/Sb/Pb, the strength of adhesive bonding can be madeto be 2.0 Kg/pin. Moreover, dispersion of the strength of adhesivebonding can be restrained. Even with the heat cycle condition and heatapplied during mounting of IC chips, reduction in the strength ofadhesive bonding of the conductive connecting pin can be prevented.Moreover, separation and inclination of the pin can be prevented. Inaddition, also electrical connection can be maintained.

Other aspects claimed in claims 53 and 54 have the structure that aplane layer which is a conductive layer is formed on the surface of thesubstrate. Moreover, the conductive connecting pin is directly connectedto the plane layer so that the electric resistance from an externalsubstrate (for example, a daughter board) to the plane layer is reduced.Thus, supply of electric power from the daughter board can befacilitated. Therefore, the plane layer constituting the power sourcelayer has a satisfactory function. Also the plane layer constituting theearth layer is connected to the earth line of the daughter board throughthe conductive connecting pin having low resistance so that theforegoing plane layer has a satisfactory function for preventing noise.The plane layer may be formed into a mesh shape. The mesh can be formedby forming a square or a circular portion in which no conductor isformed (refer to FIG. 50).

Another aspect of the present invention claimed in claim 56 has astructure that the pad, to which the conductive connecting pin issecured, is covered with an organic resin insulating layer having anopening through which the pad is partially exposed to the outside. Whenthe package substrate is joined to another substrate, such as a motherboard, through the conductive connecting pin, deviation of the positionof the conductive connecting pin and that of the socket of the motherboard sometimes causes stress to be applied to the conductive connectingpin. As an alternative to this, warp of the substrate occurs owing toheat hysteresis of the heat cycle condition, sometimes occurs. Even inthe foregoing case, the pad is held by the organic resin insulatinglayer to prevent separation from the substrate. If sufficiently largestrength of adhesive bonding cannot easily be obtained in a case ofbonding between different materials, such as between the metal pad andthe inter layer resin insulating layer, covering of the surface of thepad with the organic resin insulating layer enables great peelingstrength to be imparted.

Another aspect of the present invention claimed in claim 57 has astructure that the conductive connecting pin is made of at least onetype of metal materials selected from copper, a copper alloy, tin, zinc,aluminum and noble metal having excellent flexibility. Therefore, whenstress is applied to the pin, the pin is deflected so that the stress isabsorbed. As a result, the conductive connecting pin cannot easily beseparated from the substrate. It is preferable that the copper alloy forconstituting the conductive connecting pin is phosphor bronze whichexhibits excellent flexibility and satisfactory electric characteristicsand which permits easy processing of the conductive connecting pin.

It is preferable that the conductive connecting pin is a so-calledT-type pin incorporating a plate-like secured portion and a columnarconnection portion projecting over the central portion of the plate-likesecured portion. The plate-like secured portion is a portion which is,through the conductive adhesive agent, secured to the conductive layerwhich is formed into the pad. The foregoing plate-like secured portionis formed into an arbitrary shape including a circular shape and apolygonal shape adaptable to the size of the pad. The shape of theconnection portion is required to permit insertion into anothersubstrate. The shape may be any one of a cylindrical shape, a prismaticshape, a conical shape and a pyramid shape. Usually, one pin is providedfor the pin disposed at a usual position. Two or more connectionportions may be provided. The number of the connection portions mayarbitrarily be determined.

It is preferable that the columnar connection portion of the conductiveconnecting pin has a diameter of 0.1 mm to 0.8 mm, the length of 1.0 mmto 10 mm and the diameter of the columnar secured portion is 0.5 mm to2.0 mm. The foregoing values are arbitrarily determined according to thesize of the pad and the type or the like of another substrate which mustbe mounted.

Another aspect of the present invention claimed in claim 58 has astructure that the columnar connection portion of the conductiveconnecting pin has a constriction portion having a diameter smaller thanthat of the other portions. Therefore, flexibility is imparted to thepin. Therefore, if stress is applied to the conductive connecting pin,the connection portion is bent at the constriction portion. Therefore,stress can be absorbed so that easy separation of the conductiveconnecting pin from the substrate is prevented.

It is preferable that the conductive connecting pin is a so-calledT-type pin incorporating a plate-like secured portion and a columnarconnection portion projecting over the central portion of the plate-likesecured portion.

The plate-like secured portion is a portion which is, through theconductive adhesive agent, secured to the conductive layer which isformed into the pad. The foregoing plate-like secured portion is formedinto an arbitrary shape including a circular shape and a polygonal shapeadaptable to the size of the pad. The shape of the connection portion isrequired to permit insertion into another substrate. The shape may beany one of a cylindrical shape, a prismatic shape, a conical shape and apyramid shape. Usually, one pin is provided for the pin disposed at ausual position. Two or more connection portions may be provided. Thenumber of the connection portions may arbitrarily be determined.

It is preferable that the conductive connecting pin is structured suchthat the diameter of the plate-like secured portion is 0.5 mm to 2.0 mm,the diameter of the columnar connection portion is 0.1 mm to 0.8 mm andthe length is 1 mm to 10 mm. The foregoing values are arbitrarilydetermined according to the size of the package substrate which must besecured and the type or the like of another substrate which must bemounted.

The constriction portion is formed at an intermediate position of theconnection portion such that the diameter of the constriction portion issmaller than the diameter of the other portions. The diameter of theconstriction portion varies according to the material of the conductiveconnecting pin and the size of the conductive connecting pin. It is animportant fact that the foregoing diameter is no less than 50% nor morethan 98% of the diameter of the connection portion. If the diameter ofthe constriction portion is smaller than 50% of the diameter of theother portions, the strength of the connection portion isunsatisfactory. When the package substrate has been joined, deformationand breakage sometimes occur. If the diameter of the constrictionportion is larger than 98% of the other portion, predeterminedflexibility cannot be imparted to the connection portion. Therefore, theeffect of absorbing stress cannot be obtained. A plurality of theconstriction portions may be formed.

The material of the conductive connecting pin according to the presentinvention is not limited if the material is a metal material. It ispreferable that at least any one of metal materials, such as gold,silver, copper, nickel, cobalt, tin and lead is employed to form theconductive connecting pin. Any one of an iron alloy having trade name“COBAL” (an alloy of Ni—Co—Fe), stainless steel and a phosphor bronzewhich is a copper alloy is a preferred material because of an externalelectrical characteristic and satisfactory processability of theconductive connecting pin. Since phosphor bronze having externalflexibility is able to satisfactorily absorb stress.

Another aspect of the present invention claimed in claim 59 has astructure that the strength of adhesive bonding with the conductiveconnecting pin can be made to be 2.0 Kg/pin or greater because themelting point of the conductive adhesive agent is 180° C. to 280° C. Theforegoing strength is not considerably reduced even after thereliability test, such as a heat cycle test, or even after heat has beenapplied during mounting of IC chips. If the melting point is lower than180° C., realized strength of adhesive bonding is about 2.0 Kg/pin. Insome cases, only unsatisfactory strength of adhesive bonding of 1.5Kg/pin can be realized. What is worse, heating applied during mountingof the IC chips sometimes causes the conductive adhesive agent to bemelted. Thus, the conductive connecting pin is undesirably separated andinclined. If the melting point is higher than 280° C., the resininsulating which is the resin layer and the solder resist layer areunsatisfactory dissolved at a temperature at which the conductiveadhesive agent is dissolved. It is preferable that the temperature is200° C. to 260° C. When the conductive adhesive agent has theabove-mentioned melting point, dispersion of the strength of adhesivebonding of the conductive connecting pin can be reduced. Moreover,applied heat does not damage the resin layer which constitutes thepackage substrate.

Another aspect of the present invention claimed in claim 60 has astructure that the conductive adhesive agent is made of at least onetype of material selected from tin, lead, antimony, silver, gold andcopper. Therefore, the conductive adhesive agent having theabove-mentioned melting point can be prepared. In particular, aconductive adhesive agent containing at least tin-lead or tin-antimonyis able to realize the above-mentioned range of the melting point. Ifthe conductive adhesive agent is melted, re-fixation easily occurs.Thus, separation and inclination of the conductive connecting pin do notoccur.

When the conductive adhesive agent is made of an alloy, such as Sn/Pb,Sn/Sb, Sn/Ag or Sn/Sb/Pb, the strength of adhesive bonding can be madeto be 2.0 Kg/pin. Moreover, dispersion of the strength of adhesivebonding can be restrained. Even with the heat cycle condition and heatapplied during mounting of IC chips, reduction in the strength ofadhesive bonding of the conductive connecting pin can be prevented.Moreover, separation and inclination of the pin can be prevented. Inaddition, also electrical connection can be maintained.

To overcome the foregoing problems, crack portions of the BGA have beendetected. As a result, cracks and breakage have occurred in the metalplated layer and a connection portion between the metal plated layer andthe BGA. Thus, a fact has been detected that cracks have occurred owingto thermal stress applied when crimping has been performed during themounting process or when the duration of the heat cycle condition inwhich a high temperature and a low temperature are repeated as theconnection reliability test is 100 hours or longer. The reason for thiscan be considered that the area of bonding between the BGA and thesolder resist is too small to prevent concentration of stress. The areaof bonding is too small to obtain satisfactory great strength ofadhesive bonding.

Investigations have been performed to obtain a method capable ofovercoming the foregoing problem. As a result, a structure has beeninvented with which PGA of a projecting pin is disposed in the openingof the solder resist layer through a conductive adhesive layer as asubstitute for the BGA. The PGA is able to enlarge the area of bondingas compared with the area permitted by the BGA. Therefore, concentrationof stress can be prevented, causing a crack and breakage in the joininginterface to be prevented. Moreover, the strength of adhesive bondingcan be enlarged, and defecting connection with an external substrate canbe prevented. Since the through hole for the PGA is not required,electric wires can be disposed below the PGA. Therefore, an equivalentdegree of design freedom to that permitted by the BGA can be maintained.

The projecting pin may be inserted and disposed in a recess formed inthe periphery of the opening in the solder resist layer. The projectingpin may be disposed through a metal layer or a conductive adhesivelayer.

The electrical connection with the conductor circuit may be establishedthrough a recess as a substitute for the opening. Since the electricalconnection is established, large-capacity electric power orlarge-capacity electric signal can be transmitted to an externalsubstrate without any problem.

The opening must be electrically connected with the conductor circuit ofthe inner substrate. When a recess is formed around the opening,electrical connection through the recess is not required. If necessary,electrical connection with the conductor circuit may be established.

Preferred aspects of the present invention are as follows.

The opening in the solder resist layer has a diameter of 100 μm to 900μm. If the diameter is smaller than 100 μm, the strength of adhesivebonding of the projecting pin is sometimes reduced. If the diameter islarger than 900 μm, a merit obtain able from the connection with anexternal substrate by flip-chip mounting can be canceled. When therecess for connecting the projecting pin is formed around the opening,it is preferable that the diameter of the opening is 120 μm to 800 μm.

Two or more recess each having a diameter of 20 μm to 100 μm forconnecting the projecting pin are formed around the opening. To enlargethe strength of adhesive bonding of the projecting pin to the solderresist, it is preferable that four to eight recesses each having adiameter of 25 μm to 70 μm are formed on the diagonal.

It is preferable that each of the opening and the recesses are formedinto a circular shape. The reason for this lies in that occurrence of acorner crack can easily be prevented in the opening and a variety offorming methods may be employed. Another shape may be employed whichincludes a rectangular shape and an ecliptic shape.

The opening and the recesses are formed by any one of a photo-via,laser, drill and punching. It is preferable that photo-via is employedwhich is capable of simultaneously forming the opening and the recesses.When the metal layer is formed in the opening, the recesses may beformed by etching.

A metal layer may be formed on the conductor circuit in which theopening is exposed to the outside. The metal layer may be constituted byone or more materials selected from a group consisting of gold, silver,nickel, tin, copper, aluminum, lead, phosphorus, chrome, tungsten,molybdenum, titanium, platinum and solder. It is preferable that gold,silver, tin or nickel is employed to form the metal layer. The reasonfor this lies in that the foregoing metal materials exhibit satisfactorycorrosion resistance to prevent corrosion of the exposed conductorcircuit.

The metal layer may be made of one of the foregoing metal material or analloy with another metal material. Two or more metal layers may belaminated.

The metal layer may be formed by a method selected from electrolessplating, electroplating, substitutional plating, sputtering andevaporation. It is preferable that the electroless plating is employedbecause a uniform metal film can be formed and the cost can be reduced.

The conductive adhesive layer is formed by solder, a brazing material,granular substances and thermoplastic resin or granular substances and athermosetting resin. It is preferable that the adhesive layer is formedby the solder among the foregoing materials. The reason for this lies inthat the strength of adhesive bonding can easily be enlarged and avariety of forming methods can be employed.

When the conductive adhesive layer is formed by the solder, it ispreferable that solder which satisfies Sn:Pb=1:9 to 4:6 and which isusually employed for a printed circuit board.

The solder which does not include the lead may be used. That reason isthat it can be taken into consideration in the environment and moreoverstrength of adhesive bonding can be secured.

The forming method is arranged such that printing, potting, resistetching or plating is performed to embed the solder adhesive layer inthe opening. Another method may be employed with which the adhesivesurface of the projecting pin is subjected to plating or potting to formthe solder adhesive layer so as to be melted owing to heat or the like.

When the adhesive layer is formed by the brazing material, it ispreferable that a metal brazing material constituted by one or morematerials selected from gold, silver, copper, phosphorus, nickel,palladium, zinc, indium, molybdenum and manganese. In particular, it ispreferable that an eutectic brazing material called a “silver brazingmaterial” or a “gold brazing material” is employed. The brazing methodis performed such that a brazing material formed into a spherical shapeis introduced into the opening so as to be melted so that the adhesivelayer is formed. Another method may be employed with which coating ofportions except for the opening is performed. Then, immersion isperformed so that the material is filled in the opening. Another methodhas the steps of forming a brazing material on the adhesive surface ofthe projecting metal electrode, performing heating and melting tointroduce the brazing material into the opening. As an alternative tothis, all usual methods may be employed.

When the adhesive layer is formed by the granular substances and thethermoplastic resin or the thermosetting resin, it is preferable thatthe granular substances are made of at least one of metal particles,inorganic particles and resin particles.

The metal particles of the granular substances may be a metal material,such as copper, gold, silver, nickel, aluminum, titanium, chrome, tin,palladium or platinum. Either of the foregoing metal material may beemployed or an alloy of two or more metal materials may be employed.

The shape of the metal particles may be a spherical shape, a polygonalshape or a mixed shape of the spherical shape and the polygonal shape.The inorganic particles of the granular substances may be silica,alumina, mullite or silicon carbide.

The shape of the inorganic particle may be a spherical shape, apolygonal shape, a porous shape or a mixed shape of the spherical shapeand the polygonal shape. The surface layer of the inorganic particle iscoated with conductive substance substances, such as a metal layer or aconductive resin so that conductivity is imparted to the inorganicparticles.

It is preferable that the resin particles of the granular substances isat least any one of epoxy resin, benzoguanamine resin and amino resin.Conductive resin, such as anisotropic conductive resin, may be employedto form the inorganic particles.

The surface layers of the inorganic particles are coated with conductivesubstances, such as a metal layer or conductive resin, so thatconductivity is imparted to the resin particles. It is preferable thatepoxy resin is employed. The reason for this lies in that satisfactoryadhesiveness with the formed resin can be realized and the linearexpansion coefficients are similar to each other. Therefore, a crack ofthe formed resin can be prevented.

It is preferable that the diameter of each of the metal particles,inorganic particles or the resin particles is 0.1 μm to 50 μm. If theparticle size is smaller than 0.1 μm, electrical conduction cannotsometimes be established. If the particle size is larger than 50 mm,operability for introducing the particles into the opening deteriorates.

It is preferable that the filling factor of the metal particles, theinorganic particles or the resin particles with respect to the overallvolume is 30 wt % to 90 wt %. If the foregoing factor is lower than 30wt %, the electrical connection cannot sometimes be established. If thefactor is higher than 90 wt %, the strength of adhesive bonding with theprojecting pin is reduced.

The resin for filling the inside portion of the opening may bethermosetting resin or thermoplastic resin.

The thermosetting resin may be at least one material selected from agroup consisting of epoxy resin, polyimide resin, polyester resin andphenol resin.

The thermoplastic resin may be at least any one of materials selectedfrom a group consisting of epoxy resin, fluorine-resin polyethyleneterephthalate (PET), such as polytetrafluoroethylene (PTFE), ethylenetetra fluoride-propylene hexa fluoride copolymer (FEP) or ethylene tetrafluoride perfluoroalkoxy copolymer (PFA); polysulfon (PSF);polyphenylsulfide (PPS); thermoplastic polyphenylether (PPE); polyethersulfon (PES); polyetherimide (PEI); polyphenylsulfon (PPES);polyethylene terephthalate (PEN); polyether etherketone (PEEK); andpolyolefine resin.

The most preferred resin which must be filled in the opening is theepoxy resin. The reason for this lies in that any diluting solvent isnot required to adjust the viscosity and satisfactory strength, heatresistance and chemical resistance can be realized.

To adjust the viscosity of the filler resin may be mixed with organicsolvent, water, additives and particles.

The granular substances and the filler resin are mixed by a mixer or thelike to uniform the particle substances in the resin. Then, thematerials are introduced into the opening.

When the thermosetting resin is employed, the resin is filled in theopening by printing or potting. Then, the projecting pin is introducedto cause thermosetting to occur so that joining is performed. To removeair, gaps and excess solvent in the resin, vacuum or reduced-pressuredefoaming may be performed. Then, thermosetting may be performed.

When the thermoplastic resin is employed, the resin is molded into atablet shape. Then, the tablets are introduced into the output, and thenheating is performed. Then, the projecting pin is inserted. As analternative to this, the tablets are joined to the bonding surface ofthe projecting pin, and then heating and melting are performed. Then,the projecting pin is inserted into the opening.

The number of the projecting pin is basically one. If two or moreprojecting pins are provided, any problem arises. If two or moreprojecting pins are provided in parallel, the projecting pins may bedisposed around one projecting pin. The shape of the projection may be aconical shape, a cylindrical shape, a pyramid shape or a polygonalshape. If the employed shape permits insertion into the connectionportion of an external substrate, any shape may be employed.

It is preferable that the height of the projecting pin satisfies a rangefrom 5 μm to 50 μm.

It is preferable that the ratio of area of the bonding surface of theprojecting pin with respect to the diameter of the opening of the solderresist layer is 0.5 to 1.4. In particular, it is preferable that theratio is 0.8 to 1.2 because the process for bonding the projecting pinto the opening can be facilitated. Moreover, the projecting pin caneasily be stood erect at a right angle from the opening.

On the other hand, the bonding surface may be flat or a shape havingprojections. That is, when the recesses are formed around the opening,the pin-shape projections may be provided for the bonding surface toenlarge the strength of adhesive bonding of the pin.

It is preferable that the projecting pin is made of at least any one ofthe following materials: gold, silver, iron, copper, nickel, cobalt, tinand lead. In particular, it is preferable that iron, an iron alloy,copper or a copper alloy is employed. The reason for this lies in that,for example, covar which is an iron alloy, 42-alloy or phosphor bronzehas a proven track record as the material for the pin for the PGA.Moreover, the foregoing materials are suitable to a variety of processesfor forming projections.

The projecting pin may be made of a sole metal material, an alloy orformed into a structure covered with a metal layer made of gold, silveror nickel in order to prevent corrosion or a structure covered with ametal layer made of, for example, solder which is melted at atemperature not higher than 250° C. in order to enlarge the strength ofthe adhesive agent. The overall body of the projecting pin may be madeof metal or the basic structure may be constituted by a nonconductorsubstances, such as ceramics or nonconductive metal, in order to realizesatisfactory strength of the pin. Then, the basic structure is coatedwith a metal layer so as to establish the electrical connection.

In the present invention, the conductive adhesive layer, thejoint-permissible projecting pin or the metal layer, the conductiveadhesive layer and the joint-permissible projecting pin are provided forthe opening of the solder resist. The projecting pin is inserted intothe connection portion of the external substrate so that the conductorcircuit formed in the package substrate and the external substrate areelectrically connected to each other.

The projecting pin is so structured as to be inserted into theconnection portion of the external substrate. Therefore, when crimpingis performed during mounting on the external substrate, concentration ofstress to the projecting pin can be relaxed. Therefore, occurrence of acrack and breakage of the conductor circuit or the like which holds theprojecting pin can be prevented.

As compared with the substrate having the BGA, a large joining area canbe permitted between the PGA and the adhesive layer. Therefore, if heatcycle conditions are maintained for 1000 hours or longer, occurrence ofa crack and breakage of the projecting pin and the holding portion canbe prevented.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 (a), 1 (b), 1 (c) and 1 (d) are diagrams showing a process formanufacturing a package substrate according to a first embodiment of thepresent invention;

FIGS. 2 (a), 2 (b), 2 (c) and 2 (d) are diagrams showing a process formanufacturing a package substrate according to the first embodiment ofthe present invention;

FIGS. 3 (a), 3 (b), 3 (c) and 3 (d) are diagrams showing a process formanufacturing a package substrate according to the first embodiment ofthe present invention;

FIGS. 4 (a), 4 (b), 4 (c) and 4 (d) are diagrams showing a process formanufacturing the package substrate according to the first embodiment ofthe present invention;

FIG. 5 is a diagram showing a process for manufacturing the packagesubstrate according to the first embodiment;

FIG. 6 is a diagram showing a process for manufacturing the packagesubstrate according to the first embodiment;

FIG. 7 is a cross sectional view showing the package substrate accordingto the first embodiment;

FIG. 8 is an enlarged cross sectional view showing a portion in which aconductive connecting pin is connected to a pad in a state shown in FIG.7;

FIG. 9 (A) is a cross sectional view showing an example 1 of the firstembodiment, and FIG. 9 (B) is a view B shown in FIG. 9 (A);

FIG. 10 is a cross sectional view showing a package substrate accordingto second modification of the first embodiment;

FIG. 11 is a cross sectional view showing example 1 of the secondmodification;

FIG. 12 (A) is a cross sectional view showing a pad portion of a packagesubstrate according to example 2 of the second modification and 12 (B)is a view B of FIG. 12 (A);

FIG. 13 (A) is a cross sectional view showing a pad portion of a packagesubstrate according to example 3 of the second modification and 13 (B)is a view B of FIG. 13 (A);

FIG. 14 is a cross sectional view showing example 4 of the secondmodification;

FIG. 15 is a cross sectional view showing a package substrate accordingto a third modification;

FIG. 16 is a cross sectional view showing example 1 of the thirdmodification;

FIG. 17 is a cross sectional view showing example 2 of the thirdmodification;

FIG. 18 is a graph showing results of evaluation of the packagesubstrate according to the modifications of the first embodiment;

FIG. 19 is a diagram showing a process for manufacturing a packagesubstrate according to a second embodiment;

FIG. 20 is across sectional view showing the package substrate accordingto the second embodiment;

FIG. 21 is an enlarged cross sectional view showing a portion in whichthe conductive connecting pin shown in FIG. 20 is connected to the pad;

FIG. 22 is a cross sectional view showing a package substrate accordingto example 1 of the second embodiment;

FIG. 23 is a cross sectional view showing a package according to a firstmodification of the second embodiment;

FIG. 24 (A) is a cross sectional view showing a pad portion of thepackage substrate according to example 1 of the first modification ofthe second embodiment and FIG. 24 (B) is view B shown in FIG. 24 (A);

FIG. 25 (A) is a cross sectional view showing a pad portion of a packagesubstrate according to example 2 of the first modification of the secondembodiment and FIG. 25 (B) is view B of FIG. 25 (A);

FIG. 26 is a cross sectional view showing example 3 of the firstmodification of the second embodiment;

FIG. 27 is a cross sectional view showing a package substrate accordingto a second modification of the second embodiment;

FIG. 28 is a cross sectional view showing example 1 of the secondmodification of the second embodiment;

FIG. 29 is a cross sectional view showing example 2 of the secondmodification of the second embodiment;

FIG. 30 is a graph showing results of evaluation of the packagesubstrates according to the modifications of the second embodiment;

FIG. 31 is a diagram showing a process for manufacturing a packagesubstrate according to a third embodiment;

FIG. 32 is a cross sectional view showing the package substrateaccording to the third embodiment;

FIG. 33 (A) is an enlarged cross sectional view showing a portion inwhich the conductive connecting pin shown in FIG. 32 is connected to thepad and FIG. 33 (B) is a cross sectional view showing a modification ofthe conductive connecting pin;

FIG. 34 is a cross sectional view showing a package substrate accordingto example 1 of a first modification of the third embodiment;

FIG. 35 is a cross sectional view showing a package substrate accordingto the first modification of the third embodiment;

FIG. 36 (A) is a cross sectional view showing a pad portion of a packagesubstrate according to example 1 of the first modification of the thirdembodiment and FIG. 36 (B) is view B of FIG. 36 (A);

FIG. 37 (A) is a cross sectional view showing a pad portion of thepackage substrate according to example 2 of the first modification ofthe third embodiment and FIG. 37 (B) is view B of FIG. 37 (A);

FIGS. 38 (A) and 38 (B) are cross-sectional views showing example 3 ofthe first modification of the third embodiment;

FIG. 39 is a cross sectional view showing a package substrate accordingto a second modification of the third embodiment;

FIG. 40 is a cross sectional view showing example 1 of the secondmodification of the third embodiment;

FIG. 41 is a cross sectional view showing example 2 of the secondmodification of the third embodiment;

FIG. 42 is a graph showing results of evaluation of the packagesubstrates according to the modifications of the third embodiment;

FIG. 43 is a diagram showing a process for manufacturing a packagesubstrate according to a fourth embodiment;

FIG. 44 is a diagram showing a process for manufacturing the packagesubstrate according to the fourth embodiment;

FIG. 45 is across sectional view showing the package substrate accordingto the fourth embodiment;

FIG. 46 is a cross sectional view showing a package substrate accordingto a first modification of the fourth embodiment;

FIG. 47 is an enlarged cross sectional view showing a portion in whichthe conductive connecting pin shown in FIG. 46 is connected to the pad;

FIG. 48 is a cross sectional view showing a package substrate accordingto a second modification of the fourth embodiment;

FIG. 49 is an enlarged cross sectional view showing a portion in whichthe conductive connecting pin shown in FIG. 48 is connected to the pad;

FIG. 50 is a plan view showing a plane layer according to the fourthembodiment;

FIG. 51 is a graph showing results of evaluation of the packagesubstrates according to the fourth embodiment;

FIGS. 52 (A), 52 (B), 52 (C) and 52 (D) are diagrams showing a processfor manufacturing a package substrate according to a fifth embodiment;

FIGS. 53 (E), 53 (F), 53 (G) and 53 (H) are diagrams showing a processfor manufacturing the package substrate according to the fifthembodiment;

FIGS. 54 (I), 54 (J), 54 (K) and 54 (L) are diagrams showing a processfor manufacturing the package substrate according to the fifthembodiment;

FIGS. 55 (M), 55 (N), 55 (O) and 55 (P) are diagrams showing a processfor manufacturing the package substrate according to the fifthembodiment;

FIGS. 56 (Q) and 56 (R) are diagrams showing a process for manufacturingthe package substrate according to the fifth embodiment;

FIG. 57 is across sectional view showing the package substrate accordingto the fifth embodiment;

FIGS. 58 (Q), 58 (R) and 58 (S) are diagrams showing a process formanufacturing a package substrate according to a first modification ofthe fifth embodiment;

FIG. 59 is a cross sectional view showing a package substrate accordingto the first modification of the fifth embodiment of the presentinvention;

FIG. 60 is a cross sectional view showing a state in which an IC chiphas been mounted on the package substrate according to the fifthembodiment;

FIG. 61 (A) is a cross sectional view showing the IC chip according tothe fifth embodiment and FIG. 61 (B) is an enlarged view showing portionH shown in FIG. 60;

FIGS. 62 (A), 62 (B) and 62 (C) are diagrams showing a process formanufacturing a package substrate according to a second modification ofthe fifth embodiment;

FIGS. 63 (D) and 63 (E) are diagrams showing the package substrateaccording to the second modification of the fifth embodiment;

FIG. 64 is a diagram showing a process for manufacturing a packagesubstrate according to a third modification of the fifth embodiment;

FIGS. 65 (A), 65 (B) and 65 (C) are diagrams showing a process formanufacturing a package substrate according to a fourth modification ofthe fifth embodiment;

FIGS. 66 (A) and 66 (B) are diagrams showing a process for manufacturinga package substrate according to a fifth modification of the fifthembodiment;

FIGS. 67 (A), 67 (B) and 67 (C) are diagrams showing a process formanufacturing a package substrate according to a sixth modification ofthe fifth embodiment;

FIGS. 68 (D) and 68 (E) are diagrams showing a process for manufacturingthe package substrate according to the sixth modification of the fifthembodiment;

FIG. 69 (A) is a cross-sectional view showing a package substrateaccording to a seventh modification of the fifth embodiment and FIG. 69(B) is a cross sectional view showing a package substrate according toan eighth modification of the fifth embodiment;

FIGS. 70 (A) and 70 (B) are diagrams showing a process for manufacturinga package substrate according to the modification of the fifthembodiment;

FIGS. 71 (A), 71 (B), 71 (C), 71 (D), 71 (E) and 71 (F) are diagramsshowing a projecting pin according to each modification of the fifthembodiment;

FIGS. 72 (A), 72 (B) and 72 (C) are diagrams showing a process formanufacturing a package substrate according to a ninth modification ofthe fifth embodiment;

FIGS. 73 (D) and 73 (E) are diagrams showing a process for manufacturinga package substrate according to the ninth modification of the fifthembodiment;

FIG. 74 is graph showing results of experiments of the packagesubstrates according to the fifth embodiment and comparative examples;

FIG. 75 is a cross sectional view showing a package substrate accordingto the sixth embodiment of the present invention; and

FIG. 76 is across-sectional view showing a conventional packagesubstrate.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

Referring to FIGS. 1 to 8, a package substrate according to a firstembodiment will now be described together with a method of manufacturinga build-up substrate. Although the following method is performed by asemi-additive method, a full additive method may be employed.

(1) Initially, a core substrate having a conductive layer formed on thesurface thereof is manufactured. The core substrate may be a copper-cladlaminated pad incorporating a resin insulating substrate, such as aglass epoxy substrate, a polyimide substrate or a bismaleimide-triazineresin substrate which has two surfaces to each of which copper foil 8has been bonded (refer to FIG. 1 (a)). The copper foil 8 has either sideformed into a coarsened surface (a mat surface) so as to be made tofirmly contact with the resin substrate. A through hole is formed in thesubstrate by drilling, and then electroless plating is performed so thata through hole 9 is formed. It is preferable that the electrolessplating operation is performed by copper plating. Then, a plating resistis formed, and then an etching process is performed to form a conductivelayer 4. Note that electric plating may be performed to enlarge thethickness of the copper foil. It is preferable that also electricplating is copper plating. After electric plating has been performed,the surface of the conductive layer 4 and the inner wall of the throughhole 9 may be coarsened surfaces 4 a and 9 a (refer to FIG. 1 (b)).

The coarsening method is exemplified by a blackening(oxidizing)-reducing process, a spray process using mixed solution oforganic acid and cupric salt complex and a needle-shape alloy plating ofCu—Ni—P.

Then, the obtained substrate is cleaned with water, and then dried.Then, a resin filler 10 is filled in between the conductive layers 4 onthe surface of the substrate and the inside portion of the through hole9, and then drying is performed (see FIG. 1 (c)). Then, an unnecessaryportion of the resin filler 10 on the two sides of the substrate isground by performing belt-sander grinding to expose the conductive layer4. Thus, the resin filler 10 is mainly hardened. A recess formed betweenthe conductor layers 4 and the through hole 9 are plugged so that thesubstrate is flattened (see FIG. 1 (d)).

Then, the exposed surface of the conductive layer 4 is again providedwith a coarsened layer 11 (see FIG. 2 (a)). Note that a portionindicated with a circle shows the enlarged conductive layer 4 providedwith the coarsened layer 11. It is preferable that the coarsened layer11 is constituted by a needle alloy of Cu—Ni—P or a porous alloy layer.As an alternative to this, the coarsened layer may be formed by ablackening (oxidizing)-reducing process or an etching process. When theCu—Ni—P needle alloy layer or the porous alloy layer is employed, it ispreferable that “INTERPLATE” which is trade name of Ebara Yusilight isemployed. It is preferable that the etching process is performed byusing MECetch Bond which is trade name of MEC.

(2) A resin insulating layer 2 consisting of resin layers 2 a and 2 b isformed on each of the two sides of a circuit substrate incorporating theconductive layer 4 formed in step (1) (see FIG. 2 (b)). The resininsulating layer 2 serves as an inter layer resin insulating layer 52for a package substrate, as described later.

The resin insulating layer (herein after called the “inter layer resininsulating layer 52”) is made of a material exemplified by thermosettingresin, thermoplastic resin and their mixture resin. It is preferablethat the resin insulating layer 2 is made of an adhesive agent forelectroless plating. The most suitable adhesive agent for electrolessplating is acid subjected to a hardening process or a material obtainedby dispersing heat-resisting resin particles, which is soluble in anoxidizer, in a refractory and non-hardened heat-resisting resin. Asdescribed later, a process using solution of the oxidizer is performedso that heat-resisting resin particles are removed. Thus, a coarsenedsurface incorporating anchors in the form of an octopus trap on thesurface thereof can be formed.

It is preferable that the hardened heat-resisting resin particles of theadhesive agent for electroless plating are (1) heat-resisting resinpowder having an average particle size of 10 μm or smaller or (2) mixedparticles of particles having a relatively large average particle sizeand particles having a relatively small average particle size. Thus,more complicated anchors can be formed.

The adaptable heat-resisting resin may be, for example, epoxy resin(bis-A type epoxy resin, cresol novolac type epoxy resin or the like),polyimide resin or a composite material of the epoxy resin and thethermoplastic resin. The thermoplastic resin which must be combined maybe polyether sulfon (PES), polysulfon (PSF), polyphenylene sulfon (PPS),polyphenylene sulfide (PPES), polyphenyl ether (PPE) or polyetherimide(PI). The heat-resisting resin particles which are dissolved in acid orsolution of the oxidizer is exemplified by epoxy resin (it is preferablethat epoxy resin hardened by amine hardener is employed) amino resin orrubber, such as polyethylene rubber, polybutane rubber, polybutadienerubber or polybutyne rubber. The inter layer resin insulating layer isformed by coating or heating and pressing a resin film.

The resin film may be made of a material in which particles (hereinafter called “soluble particles”) which can be dissolved in acid or anoxidizer are dispersed in resin (herein after called “refractory resin”)which is refractory in acid or the oxidizer.

The expressions “refractory” and “soluble” employed in the presentinvention are defined such that a material which exhibits relativelyhigh dissolving rate when the material is immersed in solutioncontaining the same acid or an oxidizer for the same time is called“soluble” for convenience. On the other hand, a material exhibitingrelatively low dissolving rate is called “refractory” for convenience.

The foregoing soluble particles are exemplified by resin particle(herein after called “soluble resin particles”) which are soluble inacid resin or the oxidizer, inorganic resin particles (herein aftercalled “soluble inorganic particles”) which are soluble in acid or theoxidizer and metal particles (herein after called “soluble metalparticles”) which are soluble in acid or the oxidizer. The foregoingsoluble particles may be employed solely or two or more types of theparticles may simultaneously be employed.

The shape of the soluble particle is not limited. The shape may be aspherical shape, a crushed shape or the like. It is preferable that thesoluble particles have a uniform shape. In the foregoing case, acoarsened surface having asperities exhibiting uniform roughness can beformed.

It is preferable that the average particle size of the soluble particlesis 0.1 μm to 10 μm. If the particle size satisfies the foregoing range,particles having two or more particle sizes may be contained. Forexample, a mixture is exemplified which contains soluble particleshaving an average particle size of 0.1 μm to 0.5 μm and solubleparticles having an average particle size of 1 μm to 3 μm. As a result,a furthermore complicated coarsened surface can be formed. Moreover,excellent adhesiveness with the conductor circuit can be realized. Inthe present invention, the “particle size” of the soluble particles isthe length of the longest portion of the soluble particles.

The soluble resin particles are exemplified by particles made ofthermosetting resin, thermoplastic resin or the like. If the particlesare immersed in solution composed of acid or the oxidizer, the solubleresin particles must have a dissolving rate higher than that of therefractory resin. Any particles satisfying the foregoing requirement maybe employed.

The soluble resin particle is exemplified by epoxy resin, phenol resin,polyimide resin, polyphenylene resin, polyolefin resin and fluorineresin. The foregoing resin may solely be employed or mixture of two ormore resin materials may be employed.

The soluble resin particles may be resin particles made of rubber. Theforegoing rubber is exemplified by a variety of denatured polybutadienerubber, such as polybutadiene rubber, epoxy denatured rubber, urethanedenatured rubber or (meta) acrylonitrile denatured rubber and (meta)acrylonitrile butadiene rubber containing carboxylic group. When any oneof the foregoing rubber materials is employed, the soluble resinparticles can easily be dissolved in acid or the oxidizer. That is, whenthe soluble resin particles are dissolved by using acid, except forstrong acid, acid is able to dissolve the soluble resin particles. Whenthe soluble resin particles are dissolved by using the oxidizer,permanganic acid having relatively weak oxidizing effect is able todissolve the soluble resin particles. When chromic acid is employed,only a low concentration is sufficient to dissolve the soluble resinparticles. Therefore, the acid or the oxidizer does not remain on thesurface of the resin. As described later, when catalysts of palladiumchloride or the like are supplied after the coarsened surface has beenformed, failure of supply of the catalysts or undesirable oxidation ofthe catalysts can be prevented.

The soluble inorganic particles may be made of at least one materialselected from a group consisting of an aluminum compound, a calciumcompound, a potassium compound, a magnesium compound and a siliconcompound.

The foregoing aluminum compound is exemplified by alumina and aluminumhydroxide. The calcium compound is exemplified by calcium carbonate andcalcium hydroxide. The potassium compound is exemplified by potassiumcarbonate. The magnesium compound is exemplified by magnesia, dolomite,basic magnesium carbonate. The silicon compound is exemplified by silicaand zeolite. The foregoing material may be employed solely or two ormore materials may simultaneously be employed.

The soluble metal particles may be particles made of at least onematerial selected from a group consisting of copper, nickel, iron, zinc,lead, gold, silver, aluminum, magnesium, calcium and silicon. Theforegoing soluble metal particles may be coated with resin or the likein order to maintain the insulating characteristic.

When two or more types of the foregoing soluble particles are employedin a mixed manner, it is preferable that the combination of the twotypes of the soluble particles which must be mixed with each other is acombination of resin particles and inorganic particles. Since the twotypes of the particles have low conductivity, the insulatingcharacteristic of the resin film can be maintained. Moreover, thethermal expansion can easily be adjusted with respect to the refractoryresin. Thus, occurrence of a crack of the inter layer resin insulatinglayer constituted by the resin film can be prevented. Therefore,separation between the inter layer resin insulating layer and theconductor circuit can be prevented.

If the foregoing refractory resin is able to maintain the shape of thecoarsened surface formed by adding acid or the oxidizer to the interlayer resin insulating layer, the refractory resin is not limited to aspecific resin. The refractory resin is exemplified by thermosettingresin, thermoplastic resin and their composite material. Photosensitiveresin obtained by imparting a photosensitive characteristic to theforegoing resin may be employed. When the photosensitive resin isemployed, an opening for a via hole can be formed in the inter layerresin insulating layer by performing exposure and development processes.

Among the foregoing materials, it is preferable that a materialcontaining the thermosetting resin is employed. Thus, the shape of thecoarsened surface can be maintained against the plating solution and avariety of heating processes.

The refractory resin is exemplified by epoxy resin, phenol resin,polyimide resin, polyphenylene resin, polyolefin resin and fluorineresin. The foregoing resin may solely be employed or their mixture maybe employed. It is preferable that epoxy resin containing two or moreepoxy groups in one molecule thereof is employed. Since the foregoingcoarsened surface can be formed and excellent heat resistance can berealized, concentration of stress to the metal layer can be preventedeven under the heat cycle conditions. As a result, separation of themetal layer or the like can be prevented.

The epoxy resin is exemplified by cresol novolak epoxy resin, bis phenolA epoxy resin, bis phenol F epoxy resin, phenol novolak epoxy resin,alkyl phenol novolak epoxy resin, bis phenol F epoxy resin, naphthalenetype epoxy resin, dicyclopentadiene epoxy resin, an epoxy material of acondensate of a phenol material and an aromatic aldehyde having phenolhydroxyl group, triglycidyl isocyanate and alicyclic epoxy resin. Theforegoing material may solely be employed or two or more types maysimultaneously be employed. Thus, excellent heat resistance can berealized.

It is preferable that the soluble particles in the resin film accordingto the present invention are substantially uniformly dispersed in theforegoing refractory resin. Thus, a coarsened surface incorporatingasperities having uniform roughness can be formed. If a via hole or athrough hole is formed in the resin film, the adhesiveness of the metallayer of the conductor circuit which is formed on the foregoing holescan be maintained. A resin film containing soluble particles in only thesurface layer on which the coarsened surface will be formed may beemployed. As a result, portions of the resin film except for the surfacelayer are not exposed to the acid or the oxidizer. Thus, the insulatingcharacteristic between the conductor circuits through the inter layerresin insulating layer can reliably be maintained.

It is preferable that the amount of the soluble particles dispersed inthe refractory resin of the foregoing resin film is 3 wt % to 40 wt %with respect to the resin film. If the amount of the mixed solubleparticles is lower than 3 wt %, the coarsened surface having requiredasperities cannot sometimes be formed. If the amount is larger than 40wt %, the deep portion of the resin film is undesirably dissolved whenthe acid or the oxidizer is used to dissolve the soluble particles.Thus, the insulating characteristic between the conductor circuitsthrough the inter layer resin insulating layer constituted by the resinfilm cannot be maintained. As a result, short circuit is sometimescaused.

It is preferable that the resin film contains a hardener and othercomponents as well as the refractory resin.

The hardener is exemplified by an imidazole hardener, an amine hardener,a guanidine hardener, epoxy a duct of the foregoing hardeners, amaterial obtained by forming the foregoing hardener into a microcapsuleand an organic phosphine compound, such as triphenylphosphine ortetraphenyl phosphonium tetraphenyl borate.

It is preferable that the amount of the contained hardener is 0.05 wt %to 10 wt % with respect to the resin film. If the amount is smaller than0.05 wt %, the degree of hardening of the resin film is insufficient.Therefore, the acid or the oxidizer is excessively introduced into theresin film. As a result, the insulating characteristic of the resin filmsometimes deteriorates. If the amount is larger than 10 wt %, the excesshardener component sometimes denatures the composition of the resin. Asa result, the reliability sometimes deteriorates.

The “other component” is exemplified by an inorganic compound which doesnot exert an influence on the formation of the coarsened surface or afiller made of resin. The inorganic compound is exemplified by silica,alumina and dolomite. The foregoing resin is exemplified by polyimideresin, polyacrylic resin, polyamideimide resin, polyphenylene resin,melanin resin and olefin resin. When the foregoing filler is contained,the thermal expansion coefficients can be matched to each other, theheat resistance and chemical resistance can be improved. Therefore, theperformance of the printed circuit board can be improved.

The resin film may contain solvent. The solvent is exemplified byketone, such as acetone, methylethylketone or cyclohexane and aromatichydrocarbon, such as ethyl acetate, butyl acetate, cellosolve acetate ortoluene and xylene. The foregoing material may solely be employed or twoor more materials may simultaneously be employed.

The employed material is applied by using a roll coater or a curtaincoater, and then the material is semi-hardened so as to be formed intothe film shape.

(3) Then, an opening 6 for forming a via hole is formed in the resininsulating layer 2 in order to establish the electric connection withthe conductive layer 4 (see FIG. 2 (c)).

When the adhesive agent for electroless plating is employed, a photomaskhaving a circular pattern for forming the via hole drawn thereon isplaced. Then, exposure and development processes are performed, and thenheat hardening is performed so that the opening 6 is formed. When thethermosetting resin is employed, thermosetting is performed. Then, lasermachining is performed so that the opening 6 for the via hole is formedin the inter layer resin insulating layer. When the inter layer resininsulating layer is formed by bonding the resin film, laser machining,such as carbonic laser, YAG laser, excimer laser of UV laser, isperformed so that the opening for the via hole is formed. If necessary,a dipping process using permanganic acid or like or a dry etching usingplasma is performed to perform a desmear process.

(4) Then, the surface of the resin insulating layer 2 having the opening6 for the via hole is coarsened (see FIG. 2 (d)). When the adhesiveagent for electroless plating is employed to form the resin insulatinglayer 2, heat-resisting resin particles present on the surface of theadhesive agent for electroless plating are dissolved and removed withacid or an oxidizer. Thus, the surface of the adhesive agent 2 forelectroless plating is coarsened so that the anchors in the form of theoctopus trap are formed.

The foregoing acid may be, for example, strong acid, such as phosphoricacid, hydrochloric acid or sulfuric acid or organic acid, such as formicacid or acetic acid. It is preferable that the organic acid is employed.When the coarsening process has been performed, the metal conductivelayer 4 exposed to the outside through the opening 6 for the via hole isnot easily corroded.

On the other hand, it is preferable that the oxidizer is solution ofchromic acid or permanganate (potassium permanganate or the like).

It is preferable that the degree of coarsening is performed such thatmaximum roughness of the surface of Rmax 0.1 μm to Rmax 20 μm isrealized. If the thickness is too large, the coarsened surface caneasily be damaged and separated. If the thickness is too small, theadhesiveness deteriorates.

(5) Then, catalyst cores are supplied to the circuit board obtained bycoarsening the surface of the resin insulating layer 2. It is preferablethat the catalyst cores are supplied by using noble metal ions or noblemetal colloid. In general, palladium chloride or palladium colloid isemployed. It is preferable that a heating process is performed in orderto secure the catalyst cores. It is preferable that the catalyst coresare made of palladium.

(6) Then, electroless plating of the overall surface of the resininsulating layer 2 which has been coarsened and supplied with thecatalyst cores is performed. Thus, an electroless plated film 12 isformed (see FIG. 3 (a)). It is preferable that the thickness of theelectroless plated film 12 is 0.1 μm to 5 μm.

Then, a plating resist 3 is formed on the surface of the electrolessplated film 12 (see FIG. 3 (b)). A photosensitive resin film (a dryfilm) is laminated on the formed electroless plated film 12. Then, aphotomask (a glass substrate is a suitable mask) on which a platingresist pattern has been drawn is placed in close contact with thesurface of the photosensitive resin film. Then, exposure is performed,and then a development process is performed. Thus, the plating resist 3can be formed.

(7) Then, electric plating is performed so that an electric-plated filmis formed in a portion of the electroless plated film 12 in which theplating resist is not formed. Thus, a conductor layer 5 and a via hole 7are formed. It is preferable that the thickness is 5 μm to 20 μm. It ispreferable that the electric plating operation is performed by copperplating.

After electric plating has been performed, at least one method selectedfrom electrolytic nickel plating, electroless nickel plating orsputtering is employed to form a nickel film 14 (see FIG. 3 (c)). Thereason for this lies in that alloy plating composed of Cu—Ni—P caneasily be deposited on the nickel film 14. Since the nickel film servesas a metal resist, an effect can be obtained in that excess etching canbe prevented in the following process.

(8) Then, the plating resist 3 is removed, and then the electrolessplated film 12 present below the resist is removed by etching solution,such as mixed solution of sulfuric acid and hydrogen peroxide, sodiumpersulfate or ammonium peroxide. Thus, an independent conductor layer 5composed three layers consisting of the electroless plated film 12, theelectrolytic plated film 13 and the nickel film 14 and the via hole 7are formed (see FIG. 3 (d)). Note that the palladium catalyst cores onthe coarsened surface exposed in the non-conductive portion aredissolved and removed by chromic acid or sulphated water.

(9) Then, a coarsened layer 11 is formed on the surfaces of theconductor layer 5 and the via hole 7. Then, a layer made of theforegoing adhesive agent for electroless plating is formed as the resininsulating layer 2 (see FIG. 4 (a)).

(10) An opening 6 is formed in the resin insulating layer 2. Moreover,the surface of the resin insulating layer 2 is coarsened (see FIG. 4(b)).

(11) Then, catalyst cores are supplied to the coarsened surface of theresin insulating layer 2, and then an electroless plated film 12 isformed (see FIG. 4 (c)).

(12) Then, the plating resist 3 is formed on the surface of theelectroless plated film 12. As described above, the electrolytic platedfilm 13 and the nickel film 14 are formed in the portion in which theplating resist 3 is not formed (see FIG. 4 (d)).

(13) The plating resist 3 is removed, and then the electroless platedfilm 12 below the plating resist is removed. Then, a conductor layer(including a conductor layer serving as a pad 16 for securing theconductive connecting pin) 5 and the via hole 7 are formed. Thus, abuild-up substrate formed by six layers such that each side has threelayers is obtained (see FIG. 5).

(14) The coarsened layer 11 is provided for the conductor layer 5 andthe via hole 7 of the thus-obtained build-up substrate so as to becovered with an organic resin insulating layer 15 having an opening 18through which the pad 16 is partially exposed to the outside (see FIG.6). It is preferable that the thickness of the organic resin insulatinglayer is 5 μm to 40 μm. If the thickness is too small, the insulatingfunction deteriorates. If the thickness is too large, the opening cannoteasily be formed. What is worse, undesirable contact with solder occurs,causing a crack or the like to occur.

The resin for constituting the organic resin insulating layer may be anyone of a variety of resin materials, for example, resin obtained byhardening acrylate of bis phenol-A type epoxy resin, acrylate of bisphenol-A type epoxy resin or novolak-type epoxy resin with aminehardener or imidazole hardener.

The foregoing organic resin insulating layer having the above-mentionedstructure has an advantage that migration of lead (a phenomenon withwhich lead ions are dispersed in the organic resin insulating layer) canbe reduced. Moreover, the foregoing organic resin insulating layer hasexcellent heat resistance and alkali resistance. In addition,deterioration does not occur at a temperature (about 200° C.) at whichthe conductive adhesive agent, such as solder, is melted. In addition,decomposition can be prevented with strong base plating solution, suchas nickel plating solution or gold plating solution.

Acrylate of the novolak-type epoxy resin may be epoxy resin obtained bycausing glycidyl ether of phenol novolak or cresol novolak to react withacrylic acid or methacrylic acid. It is preferable that the imidazolehardener is in the form of liquid at 25° C. The reason for this lies inthat the liquid material permits uniform mixing.

The liquid imidazole hardener may be 1-benzyl-2-methylimidazole (tradename: 1B2MZ), 1-cyanoethyl-2-ethyl-4-methylimidazole (trade name:2E4MZ-CN) or 4-methyl-2-ethylimidazole (trade name: 2E4MZ).

It is preferable that the quantity of the imidazole hardener which mustbe added is 1 wt % to 10 wt % of the total solid component of theorganic resin insulating layer. The reason for this lies in that thequantity of addition satisfying the foregoing range permits easy uniformmixing. It is preferable that the solvent for the pre-hardeningcomposition of the organic resin insulating layer is glycol ethersolvent. The reason for this lies in that the organic resin insulatinglayer containing the foregoing composition does not generate freeoxygen, does not oxidize the surface of the pad and does not harm thehuman body.

It is preferable that the glycol ether solvent is at least either ofdiethylene glycol dimethyl ether (DMDG) or triethylene glycol dimethylether (DMTG). The foregoing solvent can completely be dissolved inbenzophenone or Michler's ketone which is a reaction initiator at atemperature of about 30° C. to about 50° C.

It is preferable that the quantity of the glycol ether solvent is 10 wt% to 40 wt % with respect to the overall weight of the compositions ofthe organic resin insulating layer.

The composition of the above-mentioned organic resin insulating layermay be added with a variety of defoaming agents, leveling agent,thermosetting resin for improving heat resistance and base resistanceand imparting flexibility and photosensitive monomer for improvingresolution. The leveling agent may be, for example, a polymer ofacrylate. It is preferable that the initiator is Ilugacur I907manufactured by Chibagaigi and the photosensitizer is DETX-Smanufactured by Nippon Kayaku. The composition of the organic resininsulating layer may be added with coloring matter or pigment. Thereason for this lies in that the circuit pattern can be shielded. It ispreferable that the coloring matter is phthalocyanine green.

The thermosetting resin which must be added may be bis phenol type epoxyresin. The bis phenol epoxy resin includes bis phenol-A type epoxy resinand bis phenol F-type epoxy resin. When importance is attached to thebase resistance, the former resin is employed. When low viscosity isrequired (when importance is attached to the coating smoothness), thelatter resin is employed.

The viscosity of the foregoing organic resin insulating layer is 0.5Pa·s to 10 Pa·s at 25° C., preferably 1 Pa·s to 10 Pa·s. The foregoingviscosity permits easy coating with a roll coater.

(15) A metal film 19, which is a corrosion-resisting metal in the formof a gold plated film or a nickel plated film-gold plated film is formedin the opening 18. Then, solder paste serving as a conductive adhesiveagent 17 is printed on the inner surface of the pad 16 which is thelower surface (a connection surface with a daughter board or a motherboard) of the package substrate. It is preferable that the viscosity ofthe solder paste satisfies a range from 50 PaS to 400 PaS. A conductiveconnecting pin 100 is joined to a proper pin holding apparatus so as tobe supported. A secured portion 101 of the conductive connecting pin 100is brought into contact with the conductive adhesive agent 17 in theopening 16. Then, a reflowing operation is performed at 240° C. to 270°C. so that the conductive connecting pin 100 is secured to theconductive adhesive agent 17 (see FIG. 7). As an alternative to this, astructure obtained by forming the conductive adhesive agent into aball-like shape or the like may be introduced into the opening. As analternative to this, joining to the plate-like secured portion of theconductive connection pin is performed to join the conductive connectionpin. Then, reflowing may be performed. FIG. 8 shows a pad portionprovided with the conductive connecting pin 100 enclosed in a circuitshown in FIG. 7, the pad portion being enlarged in FIG. 8.

The opening 18 formed in the upper surface of the package substrate 130is provided with a solder bump 60 which can be connected to an elementsuch as an IC chip.

The conductive connecting pin 100 according to the present invention isa so-called T-shape pin incorporating a plate-like secured portion 101and a columnar connection portion 102 projecting over substantially thecentral portion of the secured portion 101. The plate-like securedportion 101 is a portion which is secured to the outermost conductorlayer 5 of the package substrate serving as the pad 16 through theconductive adhesive agent 17. The shape of the secured portion 101 isformed into an arbitrary shape, such as a circular shape or a polygonalshape adaptable to the size of the pad. The shape of the connectionportion 102 may be any shape which can be inserted into the connectionportion, such as the terminal of another substrate. For example, theshape may be a cylindrical shape, a prism shape, a conical shape or apyramid shape.

Also the material of the conductive connecting pin 100 is not limited ifthe material is a metal material. It is preferable that at least any oneof metal materials, such as gold, silver, copper, iron nickel, cobalt,tin and lead is employed to form the conductive connecting pin. Any oneof an iron alloy having trade name “COBAL” (an alloy of Ni—Co—Fe),stainless steel and a phosphor bronze which is a copper alloy is apreferred material because excellent electrical characteristic andprocessability as the conductive connection pin are realized. Theconductive connection pin may be made of one type of a metal material oran alloy. The surface of the foregoing pin may be covered with anothermetal layer in order to prevent corrosion or improve strength. The pinmay be made of an insulating material, such as ceramics, and the surfacemay be covered with a metal layer.

It is preferable that the columnar connection portion 102 of theconductive connecting pin 100 has a diameter of 0.1 mm to 0.8 mm, thelength of 1.0 mm to 10 mm and the diameter of the columnar securedportion 101 is 0.5 mm to 2.0 mm. The foregoing values are arbitrarilydetermined according to the size of the pad and the type or the like ofthe socket of the mother board on which the pad is mounted.

The conductive adhesive agent 17 of the package substrate according tothe present invention may be solder (tin-lead, tin-antimony,silver-tin-copper or the like), conductive resin or conductive paste. Itis preferable that the melting point of the conductive adhesive agentsatisfies a range from 180° C. to 280° C. Thus, strength of adhesivebonding of the conductive connection pin of 2.0 Kg/pin can bemaintained. The separation and inclination of the conductive connectionpin do not occur owing to the heat cycle condition and heat applied whenthe IC chip has been mounted. Also the electrical connection can bemaintained. It is most preferable that solder is performed. The reasonfor this lies in that great connection strength with the conductiveconnection pin can be obtained, satisfactory resistance against heat canbe realized and the bonding operation can easily be performed.

When the conductive adhesive agent 17 is constituted by solder, it ispreferable that solder having a composition that Sn/Pb=95/5 or 60/40 isemployed. It is preferable that the melting point of the employed soldersatisfies a range from 180° C. to 280° C. It is most preferable that themelting point satisfies a range from 200° C. to 260° C. Thus, dispersionof the strength of adhesive bonding of the conductive connection pin canbe reduced. Moreover, applied heat does not damage the resin layer whichconstitutes the package substrate.

As shown in FIG. 8, the pad 16 is covered with the organic resininsulating layer (the through hole layer) 15 having the opening 18through which the pad 16 is partially exposed. The secured portion 101of the conductive connecting pin 100 is, through the conductive adhesiveagent 17, secured to the pad 16 exposed through the opening 18. As canbe understood from the drawing, the organic resin insulating layer 15covers the pad 16 such that the periphery of the pad 16 is held.Therefore, when stress is applied to the conductive connecting pin 100when the package substrate is mounted on the mother board, breakage ofthe pad 16 and separation from the organic resin insulating layer 15 canbe prevented. If different materials, such as the metal material andresin, are bonded, separation does not easily occur. Although thepackage substrate comprising the multilayer printed circuit board havingthe inter layer resin insulating layer has been described as an example,the structure of the first embodiment may be applied to a packagesubstrate in the form of only one substrate.

[First Modification]

FIG. 9 shows a package substrate 139 according to a first modificationof the first embodiment. FIG. 9 (A) is across sectional view showing anessential portion of the package substrate 139. FIG. 9 (B) is a view Bof FIG. 9 (A). Note that cross section A-A shown in FIG. 9 (B)corresponds to FIG. 9 (A). As shown in FIG. 9 (B), a pad 16 incorporatesa circular body 16 b for joining the conductive connecting pin 100; andan extension portion 16 a disposed in the vicinity of the body 16 b.Moreover, a signal line 16 c is connected to the body 16 b. In theforegoing embodiment described with reference to FIG. 8, the peripheryof the pad 16 is held by the inter layer resin insulating layer (theorganic resin insulating layer) 15. On the other hand, the firstmodification has a structure that the extension portion 16 a disposed inthe vicinity of the pad (the body 16 b) is covered with a solder resistlayer 15. The body 16 b is exposed through the opening 18 formed in thesolder resist layer 15.

Also the first modification has the structure that the extension portion16 a disposed in the vicinity of the pad (the body 16 b) is covered withthe solder resist layer 15. If stress is applied to the conductiveconnecting pin 100, separation from the substrate can be prevented. Onthe other hand, the body 16 b of the pad is exposed through the opening18 of the organic resin insulating layer 15. The organic resininsulating layer 15 and the extension portion 16 a are not in contactwith each other. Therefore, contact between the organic resin insulatinglayer 15 and the extension portion 16 a of the pad portion does notcause a crack to be formed in the organic resin insulating layer 15.

[Second Modification]

A package substrate 131 has a basic structure similar to that accordingto the first embodiment described with reference to FIGS. 7 and 8. Thepad 16 for securing the conductive connecting pin 100 is, through thevia hole 7, connected to a conductor layer 66 (5) which is an innerlayer of the outermost inter layer resin insulating layer 52. In thismodification, the pad 16 is not covered with the organic resininsulating layer 15 (see FIG. 10). Since the manufacturing process from(1) to (14) are the same as that according to the first embodiment,description is started at the following step (15).

(15) Solder paste (Sn/Sb=95:5) 17 which is the conductive adhesive agentis filled in the via hole 7. In this step, a mask member (not shown) isplaced on the surface of the organic resin insulating layer 15, and thensolder paste is printed. Then, reflowing is performed at 270° C. orlower.

(16) The conductive connection pin is secured to the pad by a methodwhich is the same as that according to the first embodiment.

In this modification, the area of bond between the pad 16 and thesubstrate can be enlarged by the via hole 7. Therefore, the peelingstrength of the pad 16 can be enlarged. Since the conductor layer 66which is the inner layer is a metal layer, adhesiveness with the metalpad 16 can be improved. Therefore, peeling can be satisfactorilyprevented.

The conductor layer to which the pad is connected may be provided forthe core substrate 1. As described above, the conductor layer on thecore substrate is made to firmly contact with the core substrate throughthe coarsened surface. Therefore, peeling off the pad can furthermore bereliably prevented.

a. EXAMPLE 1

The basic structure is the same as that of the second modification. Apackage substrate 132 (see FIG. 11) has a structure that the via hole 7provided with the pad 16 is covered with the organic resin insulatinglayer 15 having the opening 18 through which the pad is partiallyexposed to the outside. The package substrate 132 has the structure thatthe pad 16 is provided for the via hole 7. Moreover, the surface of thevia hole 7 is covered with the organic resin insulating layer 15.Therefore, satisfactory large peeling strength between the pad 16 andthe substrate can be realized.

b. EXAMPLE 2

The basic structure is the same as that of the example 1. A packagesubstrate 133 (see FIG. 12 (A)) has a structure that the pad 16 forsecuring one conductive connecting pin 100 is, through a plurality ofvia holes 7, connected to the conductor layer 66 which is the innerlayer of the inter layer resin insulating layer 52. As shown in FIG. 12(B), this example has a structure that six via holes 7 are formed in acircular configuration. Moreover, a pad 16 for covering each via hole 7is formed. FIG. 12 (B) is view B of FIG. 12 (A) viewed from the via hole7. Note that the position of the via hole 7 shown in FIG. 12 (B) doesnot cause the three via holes 7 shown in FIG. 12 (A) to appear on thecross section. To simplify the drawing, the via hole away from the frontorganic resin insulating layer is indicated with a dashed line.

c. EXAMPLE 3

A package substrate 134 (see FIG. 13) has the same basic structureexcept for the shape of the via hole 7 which is formed into a ring shapeas shown in FIG. 13 (B). FIG. 13 (B) is view B of FIG. 13 (A).

The area of bonding to the substrate can furthermore be enlarged by theplural via holes 7 according to example 2 and by the ring via hole 7according to example 3.

d. EXAMPLE 4

The basic structure is the same as that according to example 2 describedwith reference to FIG. 12. A package substrate 135 (see FIG. 14) has astructure that a plurality of via holes 7 formed in a circularconfiguration are as well as provided for the inter layer resininsulating layer 52 which is the inner layer. Moreover, the outer viahole 7 provided with the pad 16 and the inner via hole 7 are joined toeach other. The package substrate 135 has the structure that theplurality of the via holes 7 are joined to one another. Thus, peelingoff the pad 16 can significantly be prevented.

As described above, it is preferable that each of the modifications hasthe structure that the inner conductor layer with which the pad isprovided is provided for the core substrate 1. The conductor layer onthe core substrate is made to firmly contact with the insulatingsubstrate which is the core substrate through the coarsened surface (themat surface). When connection with the conductor layer on the coresubstrate is established, separation of the pad 16 from the inter layerresin insulating layer 52 can be prevented.

[Third Modification]

The basic structure is the same as that according to example 2 of thesecond modification. A package substrate 136 (see FIG. 15) has astructure that the conductor layer to which the pad 16 is connected ismade to be a conductor layer (a land 91) provided for the through hole 9of the core substrate 1. Moreover, the periphery of the pad 16 iscovered with the organic resin insulating layer 15. As shown in thedrawing, the pad 16 is, through the via hole 7, connected to the land 91of the through hole 9 and the resin filler 10 in the through hole 9.

That is, the characteristic of this modification is that the pad 16 isconnected to the conductor layer of the CORE SUBSTRATE 1 through the viahole 7. The conductor layer on the CORE SUBSTRATE 1 is made to firmlycontact with the insulating substrate, which is the core substrate,through the coarsened surface (the mat surface). Since the connectionwith the conductor layer on the core substrate is established, peelingoff the pad 16 from the inter layer resin insulating layer 52 can besatisfactorily prevented. Moreover, the through hole 9 and the pad 16are connected to each other through the via hole 7. Therefore, thelength of the electric wire from the conductive connecting pin 100,which is the external terminal, to an IC chip (a semiconductor chip)disposed opposite to the side on which the conductive connecting pin 100is provided, can be shortened.

a. EXAMPLE 1

The basic structure is the same as that according to the thirdmodification. A package substrate 137 (see FIG. 16) has a structure thata conductor layer 90 called “cover plating” and covering the throughhole 9 is provided for the through hole 9. Moreover, the pad 16 isconnected to the conductor layer 90 through the via hole 7 (see FIG.16).

b. EXAMPLE 2

The basic structure is the same as that of the third modification. Apackage substrate 138 (see FIG. 17) has a structure that the pad 16 isconnected to only the land 91 of the through hole 9 through the viahole. In example 2, the structure is formed such that the pad 16 isbonded to the conductive layer 4 on the surface of the core substrate 1.Thus, peeling can be prevented. Moreover, joining to the land 91 of thethrough hole is performed so that the length of the electric wire fromthe reverse side of the substrate is shortened.

[Fourth Modification]

The basic structure is the same as that of the second modification. Astructure obtained by forming solder into a ball-like shape is joined tothe conductive connection pin. Then, the conductive connection pin isdisposed.

As described above, the package substrate according to the firstembodiment is able to enlarge the strength of adhesive bonding betweenthe pad and the substrate. Therefore, separation of the conductiveconnection pin and the pad prevented with the pin can be effectivelyprevented. Therefore, reliability of the connection can be improved.

FIG. 18 shows results of evaluation of the package substrate accordingto the first embodiment. The following factors were evaluated: smalleststrength of adhesive bonding of the joined conductive connection pin,states of each pin after a heating test (reproduction of virtual ICmeasured state and evaluation performed such that a substrate having thepin is allowed to pass through a nitrogen reflow furnace set to 250° C.)and heat cycle condition (1000 cycles each consisting of one cycle inwhich 130° C./3 minutes+−65° C./3 minutes) smallest strength of adhesivebonding and conduction test.

Second Embodiment

A package substrate according to a second embodiment and a manufacturingmethod therefor will now be described. The foregoing steps (1) to (13)are similar to those according to the first embodiment described withreference to FIGS. 1 to 5. Therefore, the similar steps are omitted fromillustration and description.

-   (14) The conductor layer 5 and the coarsened layer 11 of the    build-up substrate obtained in steps in (1) to (13) and shown in    FIG. 5 are formed. Then, covering with the organic resin insulating    layer 15 having the opening 18 through which the pad 16 is exposed    is performed (see FIG. 19). It is preferable that the thickness of    the organic resin insulating layer is 5 μm to 40 μm. If the    thickness is too small, the insulating performance deteriorates. If    the thickness is too large, opening cannot be easily formed. What is    worse, undesirable contact with solder occurs, causing a crack or    the like to occur.-   (15) A metal film 19 made of corrosion resisting metal in the form    of a gold plated film or a nickel plated film-gold plated film is    formed in the opening 18. Then, the conductive adhesive agent 17 and    solder paste are printed in the opening 16 which is the lower    surface (the connection surface with the daughter board or the    mother board) of the package substrate. It is preferable that the    viscosity of the solder paste is 50 PaS to 400 PaS. The conductive    connecting pin 110 made of copper or a copper alloy is joined to a    proper pin holding apparatus so as to be supported. The secured    portion 101 of the conductive connecting pin 110 is brought into    contact with the conductive adhesive agent 17 in the pad 16. Then,    reflowing is performed at 220° C. to 270° C., and then the    conductive connecting pin 110 is secured to the conductive adhesive    agent 17 (see FIG. 20). As an alternative to this, a conductive    adhesive agent formed into a ball-like shape is introduced into the    opening. As an alternative to this, joining to the plate-like    secured portion of the conductive connecting pin is performed so    that the conductive connecting pin is joined. Then, reflowing may be    performed. FIG. 21 is an enlarged view showing the pad portion    enclosed in a circle shown in FIG. 20 and provided with the    conductive connecting pin 110.

The package substrate 230 has the upper opening 18 provided with asolder pump 230 which can be connected to an element, such as an ICchip.

The conductive connecting pin 110 according to the present inventionincorporates a plate-like secured portion 101 and a columnar connectionportion 102 projecting over substantially the central portion of thesecured portion 101. That is, the foregoing pin is a so-called T-shapepin. The coarsened layer 101 is a portion which is, through theconductive adhesive agent 17, secured to the outermost conductor layer 5of the Package substrate which is formed into the pad 16. The securedportion 101 is formed into a proper shape, for example, a circular shapeor a polygonal shape adaptable to the size of the pad. The shape of theconnection portion 102 is not limited if the employed shape permitsinsertion into the connection portion, such as a terminal, of anothersubstrate. The shape may be a cylindrical shape, a prism shape, aconical shape or a pyramid shape.

It is preferable that the material of the conductive connecting pin 110is at least one type of metal materials selected from copper, a copperalloy, tin, zinc, aluminum and noble metal. Each of the foregoingmaterial has excellent flexibility. In particular, it is preferable thatphosphor bronze, which is a copper alloy, is employed. The reason forthis lies in that excellent electric characteristics and processabilityas the conductive connecting pin can be realized. The conductiveconnecting pin may be coated with another metal layer in order toprevent corrosion or enlarge strength.

It is preferable that the diameter of the columnar connection portion102 of the conductive connecting pin 110 is 0.1 mm to 0.8 mm and thelength of the same is 1.0 mm to 10 mm. It is preferable that thediameter of the plate-like secured portion 101 is 0.5 mm to 2.0 mm. Theforegoing dimensions are arbitrarily determined according to, forexample the type of the socket of the mother board which must bemounted.

The conductive adhesive agent 17 adapted to the package substrateaccording to the present invention may be solder (tin-lead,tin-antimony, silver-tin-copper or the like), conductive resin orconductive paste, similar to the first embodiment. It is preferable thatthe conductive adhesive agent having a melting point of 180° C. to 280°C. is employed.

When the conductive adhesive agent 17 is made of solder, it ispreferable that solder having a composition that Sn/Pb=95/5 or 60/40 isemployed similar to the first embodiment. Also it is preferable that themelting point of the employed solder satisfies a range from 180° C. to280° C. It is furthermore preferable that the melting point satisfies arange from 200° C. to 260° C.

As can be understood from FIG. 21, the conductive connecting pin 110 ismade of a material, such as copper or a copper alloy, having excellentflexibility. Therefore, stress applied to the conductive connecting pin110 when, for example, the package substrate is joined to anothersubstrate can be absorbed because the connection portion 102 isdeflected as indicated with a dashed line shown in FIG. 21.

a. EXAMPLE 1

The pad 16 of a package substrate 231 according to example 1, as shownin FIG. 22, has a structure that the pad 16 is covered with the organicresin insulating layer (the through hole) 15 having the opening 18through which the pad 16 is partially exposed to the outside. Thesecured portion 101 of the conductive connecting pin 110 is, through theconductive adhesive agent 17, secured to the pad 16 exposed to theoutside through the opening 18. As can be understood from the drawing,the organic resin insulating layer 15 covers and holds the periphery ofthe pad 16. Therefore, if stress is applied to the conductive connectingpin 110 when the heat cycle is performed or when the package substrateis mounted on the mother board, breakage of the pad 16 and separationfrom the organic resin insulating layer 15 can be prevented. Ifdifferent materials, such as metal and resin, are bonded to each other,separation does not easily occur. Although the package substrate in theform of the multilayer printed circuit board having the inter layerresin insulating layer has been described, the structure of the secondembodiment can be applied to a package substrate having only onesubstrate.

[First Modification]

A package substrate 232 according to this modification has the basicstructure which is the same as that according to the second embodimentdescribed with reference to FIGS. 20 and 21. The pad 16 for securing theconductive connecting pin 110 is, through the via hole 7, connected tothe conductor layer 160 which is the inner layer of the inter layerresin insulating layer 200. A portion of the pad 16 is covered with theorganic resin insulating layer 15 (see FIG. 22). The manufacturing stepsfrom (1) to (14) are the same as those according to the secondembodiment.

(15) The via hole 7 is filled with solder paste (Sn/Sb=95:5) 17 servingas the conductive adhesive agent. A mask member (not shown) is placed onthe surface of the organic resin insulating layer 15 such that the maskmember is made in hermetic contact with the foregoing surface. Then,solder paste is printed. Then, reflowing is performed at 270° C. orlower.

(16) The conductive connecting pin is secured to the pad by the samemethod as that employed in the second embodiment. In the firstmodification, stress can significantly effectively be absorbed by theconductive connecting pin 110. Moreover, the via hole 7 enables the areaof bonding between the pad 16 and the substrate to be enlarged.Therefore, the peeling strength of the pad 16 can be enlarged. Since theconductor layer 160 which is the inner layer is a metal layer, excellentadhesiveness with the pad 16, which is made of metal, can be realized.Therefore, separation does not easily occur. Since the surface of thepad 16 is covered with the organic resin insulating layer 15, greatpeeling strength is permitted between the pad 16 and the substrate.

The conductor layer which is the inner layer and to which the pad isconnected may be provided for the core substrate 1. Since the conductorlayer on the core substrate is made to firmly contact with the coresubstrate through the coarsened surface, separation of the pad can befurthermore effectively performed.

a. EXAMPLE 1

A package substrate 233 (see FIG. 24 (A)) according to this example hasa basic structure which is the same as that according to the firstmodification. A pad 16 for securing the conductive connecting pin 110is, through a plurality of via holes 7, connected to a conductor layer160 which is the inner layer of an inter layer resin insulating layer200. In this example, as shown in FIG. 24 (B), six via holes 7 aredisposed to form a circular configuration. The pad 16 is formed to covereach via hole 7. FIG. 24 (B) is view B of FIG. 24 (A) viewed from thevia hole 7. Note that the position of the via hole 7 shown in FIG. 24(B) does not cause the three via holes 7 shown in FIG. 24 (A) to appearon the cross section. To simplify the drawing, the via hole away fromthe front organic resin insulating layer is indicated with a dashedline.

b. EXAMPLE 2

A package substrate 234 (see FIG. 25) has the same basic structureexcept for the shape of the via hole 7 which is formed into a ring shapeas shown in FIG. 25 (B). FIG. 25 (B) is view B of FIG. 25 (A).

The area of bonding to the substrate can furthermore be enlarged by theplural via holes 7 according to example 1 and by the ring via hole 7according to example 2.

c. EXAMPLE 3

The basic structure is the same as that according to example 1 describedwith reference to FIG. 24. A package substrate 235 (see FIG. 26) has astructure that a plurality of via holes 7 formed in a circularconfiguration are as well as provided for the inter layer resininsulating layer 200 which is the inner layer. Moreover, the outer viahole 7 provided with the pad 16 and the inner via hole 7 are joined toeach other. The package substrate 235 has the structure that theplurality of the via holes 7 are joined to one another. Thus, peelingoff the pad 16 can be significantly prevented.

As described above, it is preferable that each of the modifications hasthe structure that the inner conductor layer with which the pad isprovided is provided for the core substrate 1. The conductor layer onthe core substrate is made to firmly contact with the insulatingsubstrate which is the core substrate through the coarsened surface (themat surface). When connection with the conductor layer on the coresubstrate is established, separation of the pad 16 from the inter layerresin insulating layer 200 can be prevented.

[Second Modification]

The basic structure is the same as that according to example 2 of thefirst modification. A package substrate 236 (see FIG. 27) has astructure that the inner conductor layer to which the pad 16 isconnected is made to be a conductor layer (a land 91) provided for thethrough hole 9 of the core substrate 1. Moreover, the periphery of thepad 16 is covered with the organic resin insulating layer 15. As shownin the drawing, the pad 16 is, through the via hole 7, connected to theland 91 of the through hole 9 and the resin filler 10 in the throughhole 9.

That is, the characteristic of this modification is that the pad 16 isconnected to the conductor layer of the core substrate 1 through the viahole 7. The conductor layer on the core substrate 1 is made to firmlycontact with the insulating substrate, which is the core substrate,through the coarsened surface (the mat surface). Since the connectionwith the conductor layer on the core substrate is established, peelingoff the pad 16 from the inter layer resin insulating layer 200 can besatisfactorily prevented. Moreover, the through hole 9 and the pad 16are connected to each other through the via hole 7. Therefore, thelength of the electric wire from the conductive connecting pin 110,which is the external terminal, to an IC chip (a semiconductor chip)disposed opposite to the side on which the conductive connecting pin 110is provided, can be shortened.

a. EXAMPLE 1

The basic structure is the same as that according to the secondmodification. A package substrate 237 (see FIG. 28) has a structure thata conductor layer 90 called “cover plating” and covering the throughhole 9 is provided for the through hole 9. Moreover, the pad 16 isconnected to the conductor layer 90 through the via hole 7 (see FIG.28).

b. EXAMPLE 2

The basic structure is the same as that of the second modification. Apackage substrate 238 (see FIG. 29) has a structure that the pad 16 isconnected to only the land 91 of the through hole 9 through the viahole. In the foregoing examples, the pad 16 is bonded to the conductivelayer 4 on the surface of the core substrate 1 so that peeling isprevented. Since joining to the land 91 of the through hole isperformed, the length of the electric wire from the reverse side of thesubstrate is shortened.

[Third Modification]

The basic structure is the same as that of the first modification. Astructure obtained by forming solder into a ball-like shape is joined tothe conductive connection pin. Then, the conductive connection pin isdisposed.

As described above, the second embodiment has the structure that theconductive connecting pin is made of the material, such as copper or acopper alloy, having excellent flexibility. Therefore, stress which isapplied to the pin when the heat cycle test is performed or when thepackage substrate is mounted can sufficiently be absorbed. Therefore,separation of the pin from the substrate can be prevented. The packagesubstrate incorporating the foregoing conductive connecting pin is ableto prevent concentration of stress to the conductive connecting pin.Therefore, great strength of adhesive bonding is permitted between theconductive connecting pin and the pad and between the pad and thesubstrate. Therefore, excellent reliability of the connection isrealized.

FIG. 30 shows results of evaluation of the package substrate accordingto the first embodiment. The following factors were evaluated: smalleststrength of adhesive bonding of the joined conductive connection pin,states of each pin after a heating test (reproduction of virtual ICmeasured state and evaluation performed such that a substrate having thepin is allowed to pass through a nitrogen reflow furnace set to 250° C.)and heat cycle condition (1000 cycles each consisting of one cycle inwhich 130° C./3 minutes+−65° C./3 minutes) smallest strength of adhesivebonding and conduction test.

Third Embodiment

A package substrate according to a third embodiment and a manufacturingmethod therefor will now be described. The foregoing steps (1) to (13)are similar to those according to the first embodiment described withreference to FIGS. 1 to 5. Therefore, the similar steps are omitted fromillustration and description.

-   (14) The coarsened layer 11 is provided for the conductor layer 5    and the via hole 7 of the build-up substrate obtained by the    steps (1) to (13) and shown in FIG. 5. Then, covering with the    organic resin insulating layer 15 having the opening 18 through    which the pad 16 is exposed is performed (see FIG. 31). It is    preferable that the thickness of the organic resin insulating layer    is 5 μm to 40 μm. If the thickness is too small, the insulating    performance deteriorates. If the thickness is too large, opening    cannot easily be formed. What is worse, undesirable contact with    solder occurs, causing a crack or the like to occur.-   (15) A metal film 19 made of corrosion resisting metal in the form    of a gold plated film or a nickel plated film-gold plated film is    formed in the opening 18. Then, the conductive adhesive agent 17    serving as the solder paste are printed in the opening 16 which is    the lower surface (the connection surface with the daughter board or    the mother board) of the package substrate. It is preferable that    the viscosity of the solder paste is 50 PaS to 400 PaS. Moreover, a    conductive connecting pin 120 having a connection portion 102    provided with a constriction portion 103 is joined and supported by    a proper pin holding apparatus. Then, the secured portion 101 of the    conductive connecting pin 120 is brought into contact with the    conductive adhesive agent 17 in the opening 16. Then, reflowing is    performed at 240° C. to 270° C. so that the conductive connecting    pin 120 is secured to the conductive adhesive agent 17 (see FIG.    32). As an alternative to this, a structure obtained by forming a    conductive adhesive agent into a ball-like shape is introduced into    the opening. As an alternative to this, the joining to the    plate-like secured portion of the conductive connecting pin is    performed so that the conductive connecting pin is joined. Then,    reflowing may be performed. FIG. 33 (A) is an enlarged view of the    pad portion provided with the conductive connecting pin 120 enclosed    in a circle shown in FIG. 32.

The upper opening 18 of the package substrate 330 has a solder bump 60which can be connected to an element, such as an IC chip.

The conductive connecting pin 120 according to the present invention isa so-called T-shape pin incorporating a plate-like secured portion 101and a columnar connection portion 102 projecting over substantially thecentral portion of the secured portion 101. The plate-like securedportion 101 is a portion which is secured to the outermost conductorlayer 5 of the package substrate serving as the pad 16 through theconductive adhesive agent 17. The shape of the secured portion 101 isformed into an arbitrary shape, such as a circular shape or a polygonalshape adaptable to the size of the pad. The shape of the connectionportion 102 may be any shape which can be inserted into the connectionportion, such as the terminal of another substrate. For example, theshape may be a cylindrical shape, a prism shape, a conical shape or apyramid shape.

The constriction portion 103 is formed at an intermediate position ofthe connection portion 102, the constriction portion 103 having adiameter smaller than the other portions. It is an important factor thatthe diameter of the constriction portion 103 is not less than 50% normore than 98% of the other portions. If the diameter is smaller than 50%of the diameter of the other portions, the strength of the connectionportion is insufficient to prevent deformation and breakage when thepackage substrate is mounted. If the diameter of the constrictionportion is larger than 98% of the diameter of the other portions,predetermined flexibility cannot be imparted to the connection portion.Therefore, the effect of absorbing stress cannot be obtained.

The material of the conductive connecting pin according to the presentinvention is not limited if the material is a metal material. It ispreferable that at least any one of metal materials, such as gold,silver, copper, nickel, cobalt, tin and lead is employed to form theconductive connecting pin. Any one of an iron alloy having trade name“COBAL” (an alloy of Ni—Co—Fe), stainless steel and a phosphor bronzewhich is a copper alloy is a preferred material because of an externalelectrical characteristic and satisfactory processability of theconductive connecting pin. Phosphor bronze having external flexibilityis able to satisfactorily absorb stress.

It is preferable that the columnar connection portion 102 of theconductive connecting pin 120 has a diameter of 0.1 mm to 0.8 mm, thelength of 1.0 mm to 10 mm and the diameter of the columnar securedportion 101 is 0.5 mm to 2.0 mm. The foregoing values are arbitrarilydetermined according to the size of the pad and the type or the like ofanother substrate which must be mounted.

Similarly to the first embodiment, the conductive adhesive agent 17 ofthe package substrate may be solder (tin-lead, tin-antimony,silver-tin-copper or the like), conductive resin or conductive paste. Itis preferable that the conductive adhesive agent having a melting pointof 180° C. to 280° C. is employed.

When the conductive adhesive agent 17 is constituted by solder, it ispreferable that solder having a composition Sn/Pb=95:5 or 60/40 isemployed similarly to the first embodiment. It is also preferable thatthe melting point of the employed solder satisfies a range from 180° C.to 280° C. It is furthermore preferable that the range from 200° C. to260° C. is satisfied.

As can be understood from FIGS. 33 (A) and 33 (B), the conductiveconnecting pin 120 has the connection portion 102 provided with theconstriction portion 103. Therefore, satisfactory flexibility isobtained and thus the conductive connecting pin 120 can be easily bent.Thus, stress applied to the conductive connecting pin 120 when thepackage substrate is joined to the mother board or the like can beabsorbed because the connection portion 102 is bent through theconstriction portion 103.

a. EXAMPLE 1

The pad 16 of the package substrate 331 according to example 1 is, asshown in FIG. 34, covered with the organic resin insulating layer (thethrough hole layer) 15 having the opening 18 through which the pad 16 ispartially exposed to the outside. The secured portion 101 of theconductive connecting pin 120 is, through the conductive adhesive agent17, secured to the pad 16 exposed to the outside through the opening 18.As can be understood from the drawing, the organic resin insulatinglayer 15 holds and covers the periphery of the pad 16. Therefore, ifstress is applied to the conductive connecting pin 120 when the heatcycle test is performed or when the package substrate is joined to themother board, breakage of the pad 16 and separation from the organicresin insulating layer 15 can be prevented. Although the packagesubstrate in the form of the multilayer printed circuit board having theinter layer resin insulating layer has been described as an example, thestructure according to the third embodiment can be applied to a packagesubstrate constituted by only one substrate.

[First Modification]

A package substrate 332 according to this modification has a basicstructure which is the same as that according to the third embodimentdescribed with reference to FIGS. 32 and 33. The pad 16 for securing theconductive connecting pin 120 is, through the via hole 7, connected tothe conductor layer 66 which is the inner layer of the inter layer resininsulating layer 52. The organic resin insulating layer 15 covers aportion of the pad 16 (see FIG. 35). The manufacturing steps from (1) to(14) are the same as that according to the third embodiment.

(15) The via hole 7 is filled with solder paste (Sn/Sb=95:5) 17 servingas the conductive adhesive agent. A mask member (not shown) is placedand made in hermetic contact with the surface of the organic resininsulating layer 15. Then, solder paste is printed, and then reflowingis performed at 270° C. or lower.

(16) The conductive connecting pin is secured to the pad by a methodwhich is the same as that employed in the third embodiment. The firstmodification having the constriction portion 103 of the conductiveconnecting pin 110 enables satisfactory effect of absorbing stress.Moreover, the via hole 7 enables the area of bonding between the pad 16and the substrate to be enlarged. Therefore, the peeling strength of thepad 16 can be enlarged. Since the conductor layer 66, which is the innerlayer, is a metal layer, adhesiveness with the pad 16 made of the metalcan be improved. Therefore, separation can be satisfactorily prevented.Moreover, the surface of the pad 16 is covered with the organic resininsulating layer 15, great peeling strength can be obtained between thepad 16 and the substrate.

Note that the conductor layer to which the pad is connected and which isthe inner layer may be provided for the core substrate 1. As describedabove, the conductor layer on the core substrate is made to firmlycontact with the core substrate through the coarsened surface.Therefore, separation of the Pad can furthermore be reliably prevented.

a. EXAMPLE 1

The basic structure is the same as that of the first modification. Apackage substrate 333 (see FIG. 36 (A)) has a structure that the pad 16for securing one conductive connecting pin 120 is, through a pluralityof via holes 7, connected to the conductor layer 66 which is the innerlayer of the inter layer resin insulating layer 52. As shown in FIG. 36(B), this example has a structure that six via holes 7 are formed in acircular configuration. Moreover, a pad 16 for covering each via hole 7is formed. FIG. 36 (B) is view B of FIG. 36 (A) viewed from the via hole7. Note that the position of the via hole 7 shown in FIG. 36 (B) doesnot cause the three via holes 7 shown in FIG. 36 (A) to appear on thecross section. To simplify the drawing, the via hole away from the frontorganic resin insulating layer is indicated with a dashed line.

b. EXAMPLE 2

A package substrate 334 (see FIG. 37) has the same basic structureexcept for the shape of the via hole 7 which is formed into a ring shapeas shown in FIG. 37 (B). FIG. 37 (B) is view B of FIG. 37 (A).

The area of bonding to the substrate can be furthermore enlarged by theplural via holes 7 according to example 1 and by the ring via hole 7according to example 2.

c. EXAMPLE 3

A package substrate 335 (see FIGS. 38 (A) and 38 (B)) according to thisexample has the basic structure which is the same as that according toexample 1 described with reference to FIG. 36. A plurality of via holes7 disposed to form a circular configuration are as well as provided forthe inter layer resin insulating layer 52 which is the inner layer. Theouter via hole 7 and the inner via hole 7 provided with the pad 16 arejoined to each other. Since the package substrate 335 incorporates theplural via holes 7 which are joined to one another, separation of thepad 16 can considerably be reliably prevented.

As described above, it is preferable for each modification that theconductor layer which is provided with the pad and which is the innerlayer is provided for the core substrate 1. The conductor layer on thecore substrate is, through the coarsened surface (the mat surface), madeto firmly contact with the insulating substrate which is the coresubstrate. Since the connection to the conductor layer on the coresubstrate is established, the pad 16 cannot easily be separated from theinter layer resin insulating layer 52.

[Second Modification]

A package substrate 336 (see FIG. 39) according to this modification hasa basic structure which is the same as that according to example 2 ofthe first modification. The conductor layer to which the pad 16 isconnected and which is the inner layer is a conductor layer (a land 91)provided for the through hole 9 of the core substrate 1. The organicresin insulating layer 15 covers the periphery of the pad 16. As shownin the drawing, the pad 16 is, through the via hole 7, connected to theland 91 of the through hole 9 and the resin filler 10 in the throughhole 9.

That is, a characteristic of this modification is that the pad 16 isconnected to the conductor layer of the core substrate 1 through the viahole 7. The conductor layer on the core substrate 1 is made to firmlycontact with the insulating substrate which is the core substratethrough the coarsened surface (the mat surface). Since the connection tothe conductor layer on the core substrate is established, separation ofthe pad 16 from the inter layer resin insulating layer 52 can beprevented. Moreover, the through hole 9 and the pad 16 are connected toeach other through the via hole 7. Therefore, the length of the electricwire from the conductive connecting pin 120 which is an externalterminal to an IC chip (a semiconductor chip) disposed on the sideopposite to the side on which the conductive connecting pin 120 isdisposed can be shortened.

a. EXAMPLE 1

A package substrate 337 (see FIG. 40) according to this example has abasic structure which is the same as that according to the secondmodification. A conductor layer 90 called a cover plating and arrangedto cover the through hole 9 is provided for the through hole 9. The pad16 is connected to the conductor layer 90 through the via hole 7.

b. EXAMPLE 2

A package substrate 338 (see FIG. 41) according to this example has abasic structure which is the same as that according to the secondmodification. The pad 16 is connected to only the land 91 of the throughhole 9. In the foregoing examples, the pad 16 is bonded to theconductive layer 4 on the surface of the core substrate 1 so that easyseparation is prevented. Moreover, joining to the land 91 of the throughhole is performed so that the length of the electric width from thereverse side of the substrate is shortened.

[Third Modification]

The structure according to this modification is basically the same asthat according to the first modification. A structure obtained byforming solder into a ball-like shape is joined to the conductiveconnecting pin. Then, the conductive connecting pin is disposed.

As described above, the conductive connecting pin according to the thirdembodiment incorporates the columnar connection portion and a plate-likesecured portion, wherein a constriction portion having a diametersmaller than that of the other portions is provided for the columnarconnection portion. Therefore, stress which is applied to the pin whenthe heat cycle is performed or when the package substrate is mounted canbe sufficiently absorbed because the constriction portion is bent.Therefore, separation of the pin from the substrate can be prevented.The package substrate incorporating the foregoing conductive connectingpin is able to ease concentration of stress to the conductive connectingpin. Therefore, great strength of adhesive bonding is obtained betweenthe conductive connecting pin and the pad and between the pad and thesubstrate. As a result, excellent reliability in the connection can beobtained.

FIG. 42 shows results of evaluation of the package substrate accordingto the third embodiment. The following factors were evaluated: smalleststrength of adhesive bonding of the joined conductive connection pin,states of each pin after a heating test (reproduction of virtual ICmeasured state and evaluation performed such that a substrate having thepin is allowed to pass through a nitrogen reflow furnace set to 250° C.)and heat cycle condition (1000 cycles each consisting of one cycle inwhich 130° C./3 minutes+−65° C./3 minutes) smallest strength of adhesivebonding and conduction test.

Fourth Embodiment

A package substrate according to a fourth embodiment and a manufacturingmethod therefor will now be described. Steps (1) to (12) are similar tothose according to the first embodiment described with reference toFIGS. 1 to 4. Therefore, similar steps are omitted from illustration anddescription.

-   (13) The plating resist 3 of the substrate shown in FIG. 4 (d) is    removed, the electroless plated film 12 below the plating resist is    removed, the conductor layer 5, and the via hole 7 and the plane    layer 21 are formed. Thus, a build-up substrate constituted by six    layers such that three layers are provided for each side (see FIG.    43).-   (14) A coarsened layer 11 is provided for the conductor layer 5, the    via hole 7 and the plane layer 21 of the thus-obtained build-up    substrate. Then, covering with the organic resin insulating layer 15    having the opening 18 through which the pad 16 and the plane layer    21 are exposed to the outside is performed (see FIG. 44). It is    preferable that the thickness of the organic resin insulating layer    is 5 μm to 40 μm. If the thickness is too small, the insulating    performance deteriorates. If the thickness is too large, opening    cannot easily be formed. What is worse, undesirable contact with    solder occurs, causing a crack or the like to take place.-   (15) A metal film 19 in the form of a gold plated film or a nickel    plated film-gold plated film and made of corrosion resisting metal    is formed in the opening 18. Then, solder paste serving as the    conductive adhesive agent 17 is printed in the opening 18 which is    the lower surface (the connection surface with the daughter board or    the mother board) of the package substrate. It is preferable that    the viscosity outside the solder paste satisfies a range from 50 PaS    to 400 PaS. A conductive connecting pin 100 is joined to a proper    pin holding apparatus so as to be supported. A secured portion 101    of the conductive connecting pin 100 is brought into contact with    the conductive adhesive agent 17 in the opening 16. Then, a    reflowing operation is performed at 240° C. to 270° C. so that the    conductive connecting pin 100 is secured to the conductive adhesive    agent 17 (see FIG. 45). As an alternative to this, a structure    obtained by forming the conductive adhesive agent into a ball-like    shape or the like may be introduced into the opening. As an    alternative to this, joining to the plate-like secured portion of    the conductive connection pin is performed to join the conductive    connection pin. Then, reflowing may be performed.

The opening 18 formed in the upper surface of the package substrate 431is provided with a solder bump 60 which can be connected to an elementsuch as an IC chip.

The conductive connecting pin 100 according to the present invention isa so-called T-shape pin incorporating a plate-like secured portion 101and a columnar connection portion 102 projecting over substantially thecentral portion of the secured portion 101. The plate-like securedportion 101 is a portion which is secured to the outermost conductorlayer 5 of the package substrate serving as the pad 16 through theconductive adhesive agent 17. The shape of the secured portion 101 isformed into an arbitrary shape, such as a circular shape or a polygonalshape adaptable to the size of the pad. The shape of the connectionportion 102 may be any shape which can be inserted into the connectionportion, such as the terminal of another substrate. For example, theshape may be a cylindrical shape, a prism shape, a conical shape or apyramid shape.

The conductive adhesive agent 17 for use in the package substrateaccording to the present invention may be solder (tin-lead,tin-antimony, silver-tin-copper or the like), conductive resin orconductive paste. It is preferable that the melting point of theconductive adhesive agent satisfies a range from 180° C. to 280° C.

When the conductive adhesive agent 17 is constituted by solder, it ispreferable that solder having a composition that Sn/Pb=95/5 or 60/40 isemployed. It is preferable that the melting point of the employed soldersatisfies a range from 180° C. to 280° C. It is most preferable that themelting point satisfies a range from 200° C. to 260° C.

FIG. 50 is a plan view showing a plane layer 21. The plane layer 21 isprovided with a circular portion 21 a in which any conductor is notformed so as to be formed into a mesh shape. The connection portion 21 bto which the conductive connecting pin is connected is formed in aportion except for the portion 21 a in which a conductor is not formed.Note that the mesh may be formed into a rectangular shape as asubstitute for the circular shape. The mesh may be omitted from theplane layer.

As shown in FIG. 45, a package substrate 431 according to the fourthembodiment of the present invention has the plane layer 21 provided forthe surface of the substrate and constituting the power source layer.The conductive connecting pin 100 is directly connected to the planelayer 21 so that the electric resistance from the external substrate(for example, the daughter board) to the plane layer 21 is lowered. As aresult, supply of electric power from the daughter board can befacilitated. Thus, supply of large electricity to the IC chip ispermitted. As a result, the plane layer 21 constituting the power sourcelayer has a satisfactory function.

[First Modification]

FIG. 46 shows the cross section of a package substrate 432 according toa first modification of the present invention. FIG. 47 is an enlargedview showing the pad portion provided with the conductive connecting pin110 enclosed in a circle shown in FIG. 46.

The pad 16 of the package substrate 432 according to the firstmodification is, as shown in FIG. 47, covered with the organic resininsulating layer (the through hole layer) 15 having the opening 18through which the pad 16 is partially exposed to the outside. Thesecured portion 101 of the conductive connecting pin 110 is, through theconductive adhesive agent (Sn/Sb=95:5) 17, connected to the pad 16exposed to the outside through the opening 18. As can be understood fromthe drawing, the organic resin insulating layer 15 holds and covers theperiphery of the pad 16. Therefore, if stress is applied to theconductive connecting pin 110 when the heat cycle test is performed orwhen the package substrate is mounted on the mother board, breakage ofthe pad 16 and separation from the organic resin insulating layer 15 canbe prevented. If different materials, such as metal and resin, arebonded to each other, separation does not easily occur.

As shown in FIG. 46, the package substrate according to the firstmodification of the present invention has the structure that the planelayer 21 for constituting the earth layer is formed on the surface ofthe substrate. Moreover, the conductive connecting pin 110 is directlyconnected to the plane layer 21. Therefore, the electric resistance fromthe external substrate (for example, the daughter board) to the planelayer 21 is lowered. As a result, also the plane layer which constitutesthe earth layer is connected to the earth line on the daughter boardside through the conductive connecting pin having low resistance. Thus,noise elimination can be sufficiently performed.

The package substrate 432 according to the first modificationincorporates the conductive connecting pin 110 which is made of at leastone type of a material having excellent flexibility and selected fromcopper, a copper alloy, tin, zinc, aluminum and noble metal. Inparticular, it is preferable that phosphor bronze which is a copperalloy is employed because excellent electric characteristics andprocessability as the conductive connecting pin can be obtained. Theforegoing conductive connecting pin may be covered with another metallayer in order to prevent corrosion or enlarge strength.

As can be understood from FIG. 47, the conductive connecting pin 110 ismade of the material having excellent flexibility. Therefore, stressapplied to the conductive connecting pin 110 when the package substrateis joined to another substrate can be absorbed such that the connectionportion 102 is deflected as indicated with a dashed line shown in thedrawing.

[Second Modification]

FIG. 48 shows the section of a package substrate 433 according to asecond modification of the present invention. FIG. 49 is an enlargedview showing a pad portion provided with the conductive connecting pin120 enclosed in a circle shown in FIG. 48.

As can be understood from FIG. 49, the conductive connecting pin 120 ofthe package substrate 433 according to the second modification has theconstriction portion 103 provided for the connection portion 102thereof. Therefore, excellent flexibility can be obtained and,therefore, the conductive connecting pin 120 can easily be bent. Stressapplied to the conductive connecting pin 120 when the package substrateis joined to the mother board or the like can be absorbed because theconnection portion 102 is bent through the constriction portion 103.

[Third Modification]

The structure is basically the same as that according to the firstmodification. A structure obtained by forming solder into a ball-likeshape is joined to the conductive connecting pin. Then, the conductiveconnecting pin is disposed.

In the fourth embodiment, the conductive connecting pin is directlyconnected to the plane layer so that electric resistance from theexternal substrate to the plane layer is lowered. As a result, thefunction of the plane layer can be improved.

FIG. 51 shows results of evaluation of the package substrate accordingto the first embodiment. The following factors were evaluated: smalleststrength of adhesive bonding of the joined conductive connection pin,states of each pin after a heating test (reproduction of virtual ICmeasured state and evaluation performed such that a substrate having thepin is allowed to pass through a nitrogen reflow furnace set to 250° C.)and heat cycle condition (1000 cycles each consisting of one cycle inwhich 130° C./3 minutes+−65° C./3 minutes) smallest strength of adhesivebonding and conduction test.

Fifth Embodiment

A package substrate according to a fifth embodiment and a manufacturingmethod therefor will now be described.

Initially, a circuit board having a surface on which a conductor circuitis formed is manufactured. The substrate may be a resin insulatingsubstrate, such as a glass epoxy substrate, a polyimide substrate or abismaleimide-triazine resin substrate, a copper-clad laminate plate, aceramic substrate, a metal substrate or the like. An inter layer resininsulating layer is provided for the foregoing substrate, and then theinter layer resin insulating layer is coarsened so that a coarsenedsurface is formed. The overall surface of the coarsened surface issubjected to an electroless plating to have a thin thickness. Then,plating resist is formed, and then electrolytic plating is performed tohave a large thickness in the portion in which the plating resist is notformed. Then, the plating resist is removed, and then an etching processis performed so that a conductor circuit composed of the electrolyticplated film and an electroless plated film is formed. Either of theconductor circuits is constituted by a copper pattern.

The substrate having the conductor circuits formed thereon is providedwith a recess owing to the conductor circuit or the through hole. Toplug the recess, a resin filler is applied by printing or the like.After the substrate has been dried, excess portion of the resin filleris ground by a grinding operation to expose the conductor circuit to theoutside. Then, the resin filler is mainly hardened.

Then, a coarsened layer is provided for the conductor circuit. It ispreferable that the coarsened layer is a coarsened surface of copperformed by an etching process, a grinding process, an oxidizing processor an oxidizing and reduction process or a coarsened surface constituteby a plated film. It is preferable that the maximum height Ry of theasperities on the coarsened layer is 1 μm to 10 μm.

Then, an inter layer resin insulating layer is formed on the coarsenedsurface of the conductor circuit. The foregoing inter layer resininsulating layer can be formed by using an adhesive agent forelectroless plating. The adhesive agent for electroless platingconstitutes thermosetting resin as the base thereof. If necessary,hardened heat-resisting resin particles, heat-resisting resin particleswhich are dissolved in acid or an oxidizer, inorganic particles or afibrous filler may be contained in the foregoing adhesive agent forelectroless plating. The foregoing resin insulating layer is formedbetween the lower conductor circuit and the upper conductor circuit soas to be formed into the inter layer resin insulating layer.

A plurality of the foregoing resin insulating layers may be provided.For example, the lower layer is formed into a reinforcing layer made ofinorganic particles, the fibrous filler and a resin base. On the otherhand, the upper layer may be formed into the adhesive agent layer forelectroless plating. As an alternative to this, heat-resisting resinparticles which have an average particle size of 0.1 μm to 2.0 μm andwhich may be dissolved in acid or an oxidizer are dispersed inheat-resisting resin which is refractory with respect to acid or theoxidizer to form the lower layer. On the other hand, the adhesive agentlayer for electroless plating may be formed into the upper layer.

An electroless plated film having a small thickness is formed on theoverall surface of the inter layer resin insulating layer which has beencoarsened and which have been supplied with catalyst cores. It ispreferable that the electroless plated film may be an electroless copperplating film having a thickness of 0.5 μm to 5 μm, preferably 1 μm to 3μm.

Then, a photosensitive resin film (a dry film) is laminated on theformed electroless plated film. Then, a photomask (it is preferable thata glass substrate is employed) on which a plating resist pattern hasbeen drawn is made in hermetic contact with the surface of thephotosensitive resin film so as to be placed on the same. Then, exposureand a development process are performed so that a non-conductor portionhaving the plating resist pattern is formed.

Then, an electrolytic plated film is formed in the portion except forthe non-conductor portion on the electroless copper plated film. Thus, aconductor circuit and a conductive portion which is formed into the viahole are formed. It is preferable that the electrolytic plating iselectrolytic copper plating to have a thickness of 5 μm to 20 μm.

Then, etching solution, such as mixed solution of sulfuric acid andperoxide, sodium persulfate, ammonium persulfate, ferric chloride orcupric chloride is used to remove the electroless plated film. Thus, anindependent conductor circuit and a via hole constituted by two layersincorporating the electroless plated film and the electrolytic platedfilm are obtained.

The palladium catalyst cores on the coarsened surface exposed over thenon-conductor portion is dissolved and removed by chromic acid,sulphated water or the like.

Then, the coarsened layer is formed on the conductor circuit on theright side of the substrate. It is preferable that the formed coarsenedlayer is a coarsened layer of copper formed by an etching process, agrinding process, an oxidizing process or an oxidizing and reducingprocess or a coarsened layer constituted by plated film.

Then, a solder resist layer which is the organic resin insulating layeraccording to the fifth embodiment is formed on the conductor circuit.The thickness of the solder resist layer according to the presentinvention satisfies a range from 5 μm to 150 μm. In particular, it ispreferable that the thickness is 5 μm to 40 μm.

If the thickness is too small, the function of a solder dam cannot beobtained. If the thickness is too large, the opening cannot easily beformed. Moreover, undesirable contact with the solder occurs, causing acrack to be formed.

Then, the opening is formed in the solder resist layer. A metal layerconstituted by one or more types of materials selected from gold,silver, copper, nickel, tin, aluminum, lead, phosphorus, chrome,tungsten, molybdenum, titanium, platinum and solder may be formed in theopening. The metal layer may be formed by any one of plating,evaporating and sputtering capable of forming the metal layer.

Although two metal layers are formed in the following description, thenumber of the metal layer may be one or three or more. As an alternativeto this, the metal layer may be omitted. An example case in which themetal layer is provided for the opening will now be described. The metallayer is constituted by nickel or gold. The reason why the metal layeris formed is that corrosion of the exposed conductor circuit must beprevented.

A nickel plated layer is formed in the opening by electroless plating.An example of the composition of nickel plating solution is as follows:nickel sulfate by 4.5 g/l, sodium hypophosphate by 25 g/l, sodiumcitrate by 40 g/l, boric acid by 12 g/l and thiourea by 0.1 g/l (PH=11).Then, degreasing solution is used to clean the opening in the solderresist layer and the surface. Then, a catalyst, such as palladium, issupplied to the conductor portion exposed over the opening to activatethe material. Then, immersion in plating solution is performed so that anickel plated layer is formed.

It is preferable that the thickness of the nickel plated layer is 0.5 μmto 20 μm, more preferably 3 μm to 10 μm. If the thickness is too small,the connection between the solder bump and the nickel plated layercannot easily be established. If the thickness is too large, occupancyof the solder bump formed in the opening is inhibited. In the foregoingcase, peeling sometimes occurs.

After the nickel plated layer has been formed, gold plating is performedto form a gold plated layer having a thickness of 0.01 μm to 0.1 μm,preferably about 0.03 μm.

After the solder resist has been formed, an opening for exposing theconductor circuit is formed or a recess for improving adhesiveness ofthe projecting pin is formed around the opening. The recess is formed byexposing and developing. As an alternative to this, carbon dioxide gaslaser, excimer laser or YAG laser is used. As an alternative to this,punching may be employed. A plurality of the foregoing methods may beemployed without any problem.

The diameter of the opening satisfies a range from 100 mm to 900 mm. Thediameter of the recess satisfies a range from 5 mm to 70 mm. The mostsuitable shape of the opening and that of the recess are circles. Theshape may be a polygonal shape, such as a rectangular shape or the shapeof a star.

A conductive adhesive layer is formed in the opening and the recess. Theadhesive agent may be solder, a brazing material, conductive granularsubstances and thermosetting resin or conductive granular substances andthermoplastic resin. It is preferable that solder is employed to formthe adhesive layer. The reason for this lies in that great strength ofadhesive bonding can be obtained and the forming method can be selectedfrom a variety of methods.

When the adhesive layer is constituted by solder, a material in which Pbis blended by 35% to 97% is employed. The solder which does not includethe Pb, auch as Sn/Sb, Sn/Ag or Sn/Ag/cu may be used.

When the adhesive layer is constituted by the brazing material, at leastone material selected from gold, silver, copper, phosphorus, nickel,palladium, zinc, indium, molybdenum or manganese is employed. Inparticular, it is preferable that gold brazing material constituted by agold alloy or a material called a “silver brazing material” constitutedby a silver alloy is employed. The reason for this lies in thatsatisfactory conductivity can be obtained and corrosion can sufficientlybe prevented.

When the conductive granular substances and the thermosetting resin andthe thermoplastic resin are used to form the adhesive layer, it ispreferable that the granular substances are constituted by metal, aninorganic material and resin. The reason for this lies in that thelinear expansion coefficient and the melting point with respect to theresin can easily be adjusted. Moreover, dispersion and coagulation donot easily occur when mixing with resin is performed. Note thatsubstances except for the foregoing substances may be employed. Thematerial constituted by the conductive and granular substances, such asmetal or the conductive resin is, as it is, or coated with a metal layeris employed as the conductive and granular material. The materialconstituted by the non-conductive substances, such as the inorganicmaterial or the resin, is coated with the metal layer and theconductive, and then used as the conductive and granular substances. Theforegoing conductive resin is stirred, mixed and uniformly distributedin the thermosetting resin or the thermoplastic resin. Then, theforegoing material is employed to form the adhesive layer. It ispreferable that the resin is the thermosetting resin. The reason forthis lies in that a satisfactory operability can be realized at roomtemperatures and filling of the opening can be reliably performed.

The conductive adhesive layer is formed by printing, plating, potting orresist etching. The foregoing method is a method for filling the openingin the solder resist with the foregoing material. Another method may beemployed with which applying and coating of the foregoing material tothe bonding surface of the projecting pin are performed. Then, insertioninto the opening is performed.

After the adhesive layer has been formed, the projecting pin is disposedabove the opening. The number of the projecting pin may be one, or oneor more projecting pin may be provided. The material may be a metalmaterial, such as gold, silver, iron, nickel, cobalt, tin or lead or anon-conductive material, such as ceramics. In the latter case,conductive metal is used to cove the projecting pin to establish theelectrical connection.

The shape of the bonding surface of the projecting pin may be a flatshape. In a case where the recess is provided around the opening, aprojection may be provided so as to be inserted into the recess. Thepackage substrate according to this embodiment has the structure thatwhen mounting on an external substrate is performed, the projecting pindisposed on the substrate is engaged and connected to the connectionportion of the external substrate. Therefore, concentration of stressoccurring when heat crimping is performed can be relaxed. As a result, acrack and breakage of the projecting pin and the portion for holding theprojecting pin can be prevented.

Even under the heat cycle condition of the reliability test, occurrenceof a crack and breakage of the connection portion can be prevented ascompared with the substrate provided with the BGA.

A package substrate and a manufacturing method therefor according to thefifth embodiment will now be described with reference to the drawings.

The structure of a package substrate 510 according to the fifthembodiment will now be described with reference to FIGS. 59 and 60. FIG.59 shows the cross section of a package substrate (a package substrate)510 before an IC chip 590, which is a semiconductor element, is mounted.FIG. 60 shows the cross section of the package substrate 510 on whichthe IC chip 590 has been mounted and which has been joined to a motherboard (the external substrate). As shown in FIG. 60, the IC chip 590 hasbeen mounted on the upper surface of the package substrate 510. Thelower surface of the package substrate 510 is connected to a daughterboard 594.

Referring to FIG. 59, the structure of the package substrate will now bedescribed. The package substrate 510 incorporates a multilayer coresubstrate 530 having right and reverse sides on which build-up circuitlayers 580A and 580B are formed. The build-up layer 580A incorporates aninter layer resin insulating layer 550 provided with a via hole 560 anda conductor electric circuit 558; and an inter layer resin insulatinglayer 650 provided with a via hole 660 and a conductor electric circuit658. The build-up circuit layer 580B incorporates an inter layer resininsulating layer 550 provided with a via hole 560 and a conductorelectric circuit 558; and an inter layer resin insulating layer 650provided with a via hole 660 and a conductor electric circuit 658.

A projecting pin 576A for establishing the connection with a connectionportion 592 (see FIG. 60) of the IC chip 590 is disposed on the uppersurface of the package substrate 510. On the other hand, a projectingpin 576A for establishing the connection with a connection portion 596(see FIG. 60) of the daughter board (a sub-board) 594 is disposed on thelower surface. The projecting pin 576A is connected to the via hole 660and the conductor electric circuit 658 through solder 575. Although alsothe projecting pin 576A is provided for the daughter board in thisembodiment, a conventional structure may be employed in which a land isprovided for the daughter board.

The projecting pin 576A incorporates conical projections which areinserted into a connection portion 592 of the IC chip 590 and aconnection portion 596 of the daughter board 94. The projecting pin 576Ais made of covar.

A process for mounting the IC chip 590 on the package substrate 510 willnow be described with reference to FIG. 61. FIG. 61 (A) shows the ICchip before mounting, while FIG. 61 (B) is an enlarged view showing theprojecting pin 576A indicated with symbol H shown in FIG. 60.

As shown in FIG. 61 (A), the connection portion 592 of the IC chip 590and the projecting pin 576A of the package substrate 510 are locatedsuch that the two elements correspond to each other. Then, pressure isapplied in a heating state so that the projecting pin 576A is insertedinto the connection portion 592 (see FIG. 61 (B)).

Another example will now be described with reference to FIG. 70. In thisexample, a through hole serving as the connection portion 596 is formedin the daughter board 594. The locating of the package substrate 510 andthe daughter board is performed (see FIG. 70 (A)), and then pressure isapplied to the substrate 10 in a state in which no heat is applied.Then, the projecting pin 576A is inserted into the foregoing throughhole (the connection portion) 596 (see FIG. 70 (B)).

In the foregoing example, when pressure is applied in a state in whichno heat is applied, the projecting pin 576A of the package substrate isinserted into an electrode (the connection portion 596) of the daughterboard 594. Thus, stress which is applied when the crimping process isperformed can be relaxed. Therefore, occurrence of a crack and breakageof the projecting pin and the holding portion (the solder portion) 575for the projecting pin at the time of the mounting operation can beprevented. Since a large joining area is permitted between theprojecting pin 576A and the adhesive layer (the solder layer) 575, thestrength of adhesive bonding can be enlarged as compared with theconventional structure constituted by the solder bump.

An embodiment of the projecting pin will now be described with referenceto FIG. 71. Basically, the projecting pin 576A has one projecting pin576 a as shown in FIG. 71 (A). Two or more projecting pins 576C may beprovided as shown in FIG. 71 (C) without any problem. If two or moreprojecting pins are provided, parallel disposition is permitted tosurround one projecting pin. The shape of the projecting 576 a is formedinto the conical shape. As an alternative to this, a projecting pin 576Bformed into a cylindrical shape as shown in FIG. 71 (B) may be employed.

It is preferable that the lower surface (the bonding surface) of theprojecting pin 576A is flat. If a recess is provided around the opening,a projecting pin 576D formed as shown in FIG. 71 (D) may be employedsuch that a pin-shape projection 576 b is provided for the bondingsurface (the bottom surface). Thus, the strength of adhesive bonding ofthe projecting pin can be enlarged.

The projecting pin 576A is made of covar and 42-alloy which are ironalloys and phosphor bronze which is a copper alloy. The projecting pin576A is, as shown in FIGS. 71 (A), 71 (C) and 71 (D), constituted by onetype of metal or an alloy. As an alternative to this, projecting pins576B and 576E shown in FIGS. 71 (B) and 71 (E) may be employed which aremade of ceramic 77 in order to enlarge the strength. Then, the surfaceof the projecting pin is coated with a metal layer.

An example of the method of manufacturing the package substrateaccording to the fifth embodiment will now be described.

Manufacture of Package Substrate

-   (1) A starting material was a copper-clad laminate plate 530A    structured such that copper foil 532 having a thickness of 18 μm was    laminated on each of the two sides of a substrate 530 made of glass    epoxy resin or BT (bismaleimide-triazine) resin (step (A) shown in    FIG. 52). Initially, a hole was formed in the copper-clad laminate    plate 530A by drilling, and then electroless plating was performed.    Then, etching was performed to correspond to the pattern. Thus, an    inner copper pattern 534 and a through hole 536 were formed on each    of the two sides of the substrate 530 (step (B) shown in FIG. 52).-   (2) The substrate 530 having the inner copper pattern 34 and the    through hole 536 was cleaned with water, and then the substrate 530    was dried. Then, oxidizing bath (a blackening bath) composed such    that NaOH (10 g/l), NaClO2 (40 g/l) and Na3O4 (6 g/l) and reducing    bath composed of NaOH (10 g/l) and NaBH4 (6 g/l) were used so that    oxidizing-reducing process was performed. Thus, a coarsened layer    538 was formed on the surfaces of the inner copper pattern 534 and    the through hole 536 (step (C) shown in FIG. 52).-   (3) A raw material composition for preparing a resin filler was    mixed and kneaded so that the resin filler was prepared.-   (4) The resin filler prepared in step (3) was applied to the two    sides of the substrate 530 by using a roll coater within 24 hours    from the preparation. Thus, the resin filler was filled between the    inner copper pattern 34 and the inner copper pattern 534 or in the    through hole 536. Then, the resin filler was dried at 70° C. for 20    minutes. Also another surface was subjected to a similar process.    Thus, the resin filler 540 was filled between the inner copper    patterns 534 or in the through hole 536. Then, the resin filler 540    was dried at 70° C. for 20 minutes (step (D) shown in FIG. 52).-   (5) Either side of the substrate 530 subjected to step (4) was    ground by belt sander grinding using a #600 belt grinding paper    (manufactured by Sankyo). Then, buffing was performed.

Then, a heat process was performed at 120° C. for one hour and at 150°C. for one hour so that the resin filler 540 was hardened.

-   (6) The package substrate having the conductor circuit formed    thereon was decreased with an alkaline material so that soft etching    was performed. Then, a process was performed by using catalyst    solution composed of palladium chloride and organic acid so that Pd    catalyst was supplied. The foregoing catalyst was activated, and    then immersed in electroless plating solution composed of copper    sulfate by 3.2×10⁻² mol/l, nickel sulfate by 3.9×10⁻³ mol/l, a    complexing agent by 5.4×10⁻² mol/l, sodium hypophosphite by 3.3×10⁻¹    mol/l, boric acid 5.0×10⁻¹ mol/l and surface active agent (Surfil    465 manufactured by Nissin) by 0.1 g/l and having PH=9. One minute    after the immersion, vertical vibrations and lateral vibrations were    performed one time/four second. Thus, a coating layer constituted by    a needle alloy composed of Cu—Ni—P and a coarsened layer 542 were    formed on the surface of the inner copper pattern 534 and that of a    land 536 a of the through hole 536 (step (F) shown in FIG. 53). The    maximum height of asperities of the coarsened layer 542 was 3 μm.

After the coarsened layer was formed, Cu—Sn substitution reaction wascaused to take place under conditions that tin borofluoride by 0.1mol/l, thiourea by 1.0 mol/l, the temperature was 35° C. and PH=1.2.Thus, an Sn layer (not shown) having a thickness of 0.3 μm was formed onthe surface of the coarsened layer.

-   (7) A raw material for preparing the inter layer resin insulating    material was stirred and mixed so that the viscosity was adjusted to    1.5 Pa·s. Thus, an inter layer resin insulating material (for the    lower layer) was obtained.

Then, a raw material composition for preparing the adhesive agent forelectroless plating was stirred and mixed so that the viscosity wasadjusted to 7 Pa·s. Thus, the adhesive agent solution for electrolessplating (for the upper layer) was obtained.

-   (8) The two sides of the substrate 530 manufactured in step (6) was    coated with the inter layer resin insulating material (for the lower    layer) 44 obtained in step (7) and having the viscosity of 1.5 Pa·s    by a roll coater 24 hours after the preparation. Then, the substrate    530 was allowed to stand for 20 minutes in a horizontal state. Then,    drying (prebaking) was performed at 60° C. for 30 minutes. Then, the    photosensitive adhesive solution (for the upper layer) 46 obtained    in step (7) and having the viscosity of 7 Pa·s was applied 24 hours    after the prepared. Then, the substrate 530 was allowed to stand for    20 minutes in the horizontal state. Then, drying (prebaking) at    60° C. was performed for 30 minutes. Thus, an adhesive layer 550 a    having a thickness of 35 μm was formed (step (G) shown in FIG. 53).-   (9) A photomask film 551 having a printed black circle 551 a having    a diameter of 85 mm was made in hermetic contact with each of the    two sides of the substrate 530 having the adhesive layer 550 a    formed in step (8). Then, an extra-high pressure mercury lamp was    operated to perform exposure with 500 mJ/cm2 (step (H) shown in FIG.    53). Then, spray development was performed by using DMTG solution.    Then, the substrate was exposed with the extra-high pressure mercury    lamp with 3000 mJ/cm2, and then a heating process was performed at    100° C. for one hour, 120° C. for one hour and 150° C. for three    hours (post baking). Thus, an inter layer resin insulating layer (a    two-layer structure) 550 incorporating an opening (an opening for    forming the via hole) 48 having a diameter of 85 mm, corresponding    to the photomask film, exhibiting excellent dimension accuracy and    having a thickness of 35 mm was formed (step (I) shown in FIG. 54).    Note that the tin plated layer (not shown) was partially exposed in    the opening 548 for a via hole.

The inter layer resin insulating layer can be made by using a resin filmof which the via hole is formed by the photo or the laser.

-   (10) The substrate 530 having the formed opening 48 was immersed in    chromic acid for 19 minutes. Then, epoxy resin particles present on    the surface of the inter layer resin insulating layer 550 were    dissolved and removed so that the surface of the inter layer resin    insulating layer 550 was coarsened (step (J) shown in FIG. 54).    Then, the substrate 530 was immersed in neutral solution    (manufactured by Shiplay), and then the substrate 530 was cleaned    with water.

Then, palladium catalyst (manufactured by Atotech) was supplied to thesurface of the substrate subjected to the coarsened process (a depth ofcoarsening was 6 μm) so that catalyst cores (not shown) were supplied tothe surface of the inter layer resin insulating layer 550 and the innersurface of the opening 548 for a via hole.

-   (11) The substrate was immersed in electroless copper plating    solution having the following composition so that an electroless    copper-plated film 552 having a thickness of 0.6 μm to 1.2 μm was    formed on the overall surface of the coarsened surface (step (K)    shown in FIG. 54).    [Electroless Plating Solution]

EDTA 0.08 mol/l Copper Sulfate 0.03 mol/l HCHO 0.05 mol/l NaOH 0.05mol/l a,a′-bipyridyl 80 mg/l PEG 0.10 g/l[Electroless Plating Conditions]

20 minutes such that the resin of the solution was 65° C.

-   (12) A marketed photosensitive dry film was applied to the surface    of the electroless copper-plated film 552 formed in step (11). Then,    a mask was placed, and then, exposure was performed with 100 mJ/cm².    Then, a development process was performed by using 0.8% sodium    carbonate. Thus, a plating resist 554 having a thickness of 15 μm    was formed (step (L) shown in FIG. 54).-   (13) Then, the portion in which no resist was formed was subjected    to electrolytic copper plating under the following conditions so    that an electrolytic copper-plated film 556 having a thickness of 15    μm was formed (step (M) shown in FIG. 55).    [Electrolytic Plating Solution]

Sulfuric Acid 2.24 mol/l Copper Sulfate 0.26 mol/l Additive (CAPALASIDEHL manufactured by ATOTECH) 19.5 ml/l[Electrolytic Plating Conditions]

Density of Electric Current 1 A/dm2 Duration 65 minutes Temperature 22 ±2° C.

-   (14) The plating resist 554 was separated and removed by using 5%    KOH. Then, the electroless plated film below the plating resist was    etched with mixed solution of sulfuric acid and hydrogen peroxide so    as to be dissolved and removed. Thus, a conductor electric circuit    558 composed of the electroless copper plated film and the    electrolytic copper plated film and a thickness of 18 μm and a via    hole 560 were formed (step (N) shown in FIG. 55).-   (15) A process similar to that in step (6) was performed so that a    coarsened layer 562 made of Cu—Ni—P was formed. Then,    Sn-substitution of the surface was performed (step (O) shown in FIG.    55).

Without using the plating alloy, the coarsened layer can be made by theetching (second copper complex and organic acid salt).

-   (16) Steps (7) to (15) were repeated so that the upper conductor    electric circuit 658 and the via hole 660 (the conductor circuit)    were formed. Thus, a multilayer printed circuit board was obtained    (step (P) shown in FIG. 55). Note that the Sn substitution was not    performed.-   (17) On the other hand, 46.67 g of oligomer (having a molecular    weight of 4000) which was obtained by forming 50% of epoxy bases of    60 wt % cresol novolak epoxy resin (manufactured by Nippon Kayaku)    dissolved in DMDG into acrylic material and with which was given the    photosensitive characteristic, 15.0 g of 80 wt % bis phenol A-type    epoxy resin (EPICOAT manufactured by Yuka Shell) dissolved in methyl    ethyl ketone, 1.6 g of imidazole hardener (2E4MZ-CN manufactured by    Shikoku Kasei), 3 g of polyhydric acrylic monomer (R604 manufactured    by Nippon Kayaku) which is photosensitive monomer, 1.5 g of    polyhydric acrylic monomer (DPE6A manufactured by Kyoeisha) and 0.71    g of dispersing defoaming agent (S-65 manufactured by Sannopko) were    mixed with one another. Then, 2 g of benzophen one (manufactured by    Kanto Kagaku) serving as a photoinitiator and 0.2 g of Michler's    ketone (manufactured by Kanto Kagaku) serving as a photosensitizer    were added. Then, the viscosity was adjusted to 2.0 Pa·s at 25° C.    so that a solder resist composition was obtained.-   (18) Each of the two sides of the multilayer circuit board obtained    in step (16) was coated with the foregoing solder resist composition    to have a thickness of 20 μm. Then, a drying process was performed    at 70° C. for 20 minutes and 70° C. for 30 minutes. Then, a    photomask film (not shown) having a circular pattern (a mask    pattern) for forming the opening and the recess around the opening    and having a thickness of 5 mm was disposed in close contact. Then,    exposure was performed with ultra violet rays with 500 mJ/cm² so    that a recess 571 b was formed around the opening (step (B) shown in    FIG. 62) Then, photomask film (not shown) having a circular pattern    (a mask pattern) for forming the opening drawn thereon and having a    thickness of 5 mm was placed in closed contact. Then, exposure was    performed with ultra violet rays with 1000 mJ/cm², and then the DMTG    development process was performed. Then, a heating process was    performed at 80° C. for one hour, 100° C. for one hour, 120° C. for    one hour and 150° C. for three hours so that the solder pad portion    (including the via hole and its land portion) was formed into the    opening 571 (having a diameter of 200 μm). Thus, a solder resist    layer (having a thickness of 20 μm) 570 was formed (step (Q) shown    in FIG. 56).-   (19) Then, solder 575 having a composition that Sn/Pb=4:6 and    serving as the adhesive layer was formed on the surface of the    opening 571 of the solder resist layer 570 to have a thickness of 18    μm (step (R) shown in FIG. 56).

On the other hand, the projecting pin 576A constituted by 42-alloy wassupported by a pin holding jig (not shown). Then, flux was applied tothe inner surface of the opening 571, and then reflowing was performedin a state in which the jig holding the projecting pin 576A was madecontact with the package substrate so that the projecting pin 576A wasconnected to the solder 575. Thus, a package substrate 510 having theprojecting pin metal pin was obtained (see FIG. 57).

(First Modification)

The basic structure was the same as that according to the fifthembodiment. A metal layer was formed on the inner surface of theopening.

Steps (1) to (18) were the same as those according to the fifthembodiment. An opening 571 having an opening 571 was formed (step (Q)shown in FIG. 58).

-   (19) The substrate having the opening in the solder resist layer    hereof was immersed in an electroless nickel plating solution    composed of nickel chloride by 30 g/l, sodium hypophosphite by 10    g/l and sodium citrate by 10 g/l and having pH=5 for 20 minutes.    Thus, a nickel layer 572 having a thickness of 5 μm was provided for    the opening. Then, the substrate 530 was immersed in an electroless    plating solution composed of gold cyanide potassium by 2 g/l,    ammonium chloride by 75 g/l, sodium citrate by 50 g/l and sodium    hypophosphite by 10 g/l at 93° C. for 23 seconds. Thus, a    gold-plated layer 574 having a thickness of 0.03 μm was formed on    the nickel layer 572 (step (R) shown in FIG. 58)-   (20) Then, solder 575 having a composition that Sn/Pb=4:6 serving as    the adhesive layer for the opening 571 of the solder resist layer    570 was formed by mask printing to have a thickness of 18 mm.

On the other hand, the projecting pin 576A constituted by 42-alloy wassupported by a pin holding jig (not shown). Then, flux was applied tothe inner surface of the opening 571, and then reflowing was performedat 200° C. in a state where the jig supporting the projecting pin 576Awas made contact with the package substrate so that the connection wasestablished. Thus, a package substrate 510 incorporating the projectingmetal pin was obtained (see FIG. 59).

(Second Modification)

The basic structure was the same as that according to the fifthembodiment. Four recesses were formed around each opening 571.

Steps (1) to (17) were the same as those according to the fifthembodiment.

-   (18) Each of the two sides of the multilayer circuit board 10    obtained in step (16) was coated with the solder resist composition    70 to have a thickness of 20 μm (step (A) shown in FIG. 62). Then, a    drying process was performed at 70° C. for 20 minutes and 70° C. for    30 minutes. A photomask film (not shown) having a circular pattern    (a mask pattern) for forming the opening and the recess around the    opening and having a thickness of 5 mm was disposed in close    contact. Then, exposure was performed with ultra violet rays with    500 mJ/cm², and then the DMTG development process was performed.    Then, a heating process was performed at 80° C. for one hour,    100° C. for one hour, 120° C. for one hour and 150° C. for three    hours. Thus, the solder pad portion (including the via hole and its    land portion) was formed into the opening 571 (having a diameter of    150 μm). Thus, a solder resist layer (having a thickness of 20 μm)    70 having four recesses 571 b each having a diameter of 10 μm and a    depth of 10 μm around the opening 571 on the diagonal was formed    (step (C) shown in FIG. 62).-   (19) As the adhesive layer of the opening 571 of the solder resist    layer 570, solder 575 having a composition that Sn/Pb=4:6 was formed    by mask printing to have a thickness of 18 μm (step (D) shown in    FIG. 63).

On the other hand, the projecting pin 576D (see FIG. 71 (D)) constitutedby 42-alloy was supported by a pin holding jig (not shown). Then, fluxwas applied to the inner surface of the opening 571, and then reflowingwas performed to establish the connection in a state in which the jigsupporting the projecting pin 576D was made contact with the packagesubstrate. Thus, a package substrate 510 having the projecting metal pinwas obtained (step (E) shown in FIG. 63).

(Third Modification)

The structure was basically the same as that according to the secondmodification. As shown in FIG. 64, a metal layer was formed in theopening 571. Similarly to the first modification, the metal layer wassuch that the nickel layer 572 and the gold-plated layer 574 wereformed.

(Fourth Modification)

The basic structure was the same as that according to the firstmodification. As the metal layer, an aluminum layer was formed in theopening. Steps (1) to (18) were the same as those according to the firstmodification.

-   (19) The substrate 530 having the opening 571 formed in the solder    resist layer 570 was subjected to the following process: an aluminum    layer 672 was, by sputtering, formed on the conductor electric    circuit 658 and the via hole 660 through which the opening 571 was    exposed to the outside to have a thickness of 4 μm (step (A) shown    in FIG. 65).-   (20) Silver brazing material (BAg-8) 75 C in a quantity of 0.1 g was    placed on the aluminum layer 672 of the opening 571 so as to be    dissolved (step (B) shown in FIG. 65). Then, a projecting pin 576A    made of covar was placed on the dissolved silver brazing material    75C so as to be joined by crimping. Thus, a package substrate was    obtained (step (C) shown in FIG. 65).    (Fifth Modification)

The basic structure was the same as that according to the fifthembodiment. The metal particles in the adhesive layer was copper, whilepolyimide resin was employed as the thermoplastic resin.

Steps (1) to (18) were the same as those according to the firstmodification.

-   (19) The adhesive agent was prepared by using metal particles and    thermoplastic resin. Copper which was metal particles was formed    into spherical shapes having a diameter of 1 μm and a diameter of    0.6 μm, respectively. The molded copper particles arranged such that    copper particles having the diameter of 1 μm and those having the    diameter of 0.6 μm were blended at a ratio of 3:1, as the    thermoplastic resin, stirred in polyimide resin such that    coagulation was prevented. The filling factor was made to be 85%.    Thus, a tablet 675 having a diameter of 50 μm and a thickness of 10    μm was molded.-   (20) The molded tablet 675 was inserted into the opening 571    (step (A) shown in FIG. 66), and then the substrate was heated to    200° C. Then, a projecting pin 576A made of covar was placed, and    then crimping was performed to perform joining. Thus, a package    substrate was obtained (step (B) shown in FIG. 66).    (Sixth Modification)

The basic structure was the same as that according to the thirdmodification. An Sn layer was provided for the metal layer by Cu—Snsubstitutional reaction. As the adhesive layer, silica was employed asthe inorganic particle and epoxy resin was employed as the thermosettingresin.

Steps (1) to (16) were the same as those according to the fifthembodiment.

-   (17) Before the solder resist layer was formed, the surface of the    coarsened layer of the conductor circuit was tin-substituted so that    a tin layer having a thickness of 0.3 μm was formed.-   (18) On the other hand, 46.67 g of oligomer (having a molecular    weight of 4000) which was obtained by forming 50% of epoxy bases of    60 wt % cresol novolak epoxy resin (manufactured by Nippon Kayaku)    dissolved in DMDG into acrylic material and with which was given the    photosensitive characteristic, 15.0 g of 80 wt % bis phenol A-type    epoxy resin (EPICOAT 1001 manufactured by Yuka Shell) dissolved in    methyl ethyl ketone, 1.6 g of imidazole hardener (2E4MZ-CN    manufactured by Shikoku Kasei), 3 g of polyhydric acrylic monomer    (R604 manufactured by Nippon Kayaku) which is photosensitive    monomer, 1.5 g of polyhydric acrylic monomer (DPE6A manufactured by    Kyoeisha) and 0.71 g of dispersing defoaming agent (S-65    manufactured bySannopko) were mixed with one another. Then, 2 g of    benzophen one (manufactured by Kanto Kagaku) serving as a    photoinitiator and 0.2 g of Michler's ketone (manufactured by Kanto    Kagaku) serving as a photosensitizer were added. Then, the viscosity    was adjusted to 2.0 Pa·s at 25° C. so that a solder resist    composition was obtained.

Note that the viscosity was measured by using No. 4 rotor of a B-typeviscometer (DVL-B manufactured by Tokyo Keiki) when the velocity was 60rpm and No. 3 rotor of the same when the velocity was 6 rpm.

-   (19) The solder resist composition 70 was applied to each side of    the multilayer circuit board obtained in step (17) to have a    thickness of 20 μm (step (A) shown in FIG. 67). Then, a drying    process was performed at 70° C. for 20 minutes and 70° C. for 30    minutes. Then, a photomask film (not shown) having a circular    pattern (a mask pattern) drawn thereon and a thickness of 5 mm was    made in hermetic contact and placed. Then, exposure was performed    with ultra violet rays with 1000 mJ/cm², and then a DMTG development    process was performed. Then, a heat process was performed at 80° C.    for one hour, 100° C. for one hour, 120° C. for one hour and 150° C.    for three hours. Thus, a solder resist layer (having a thickness of    20 μm) 70 having the opening 571 (having a diameter of 200 μm)    constituted by the solder pad portion (including the via hole and    its land portion) was formed (step (B) shown in FIG. 67).-   (20) Two recesses 571 b each having a diameter of 50 μm and a depth    of 15 μm were formed around the opening 571 by using a drill 630    having a diameter of 50 μm (step (C) shown in FIG. 67).-   (21) The adhesive agent was constituted by inorganic particles and    thermosetting resin. Silica in the form of inorganic particles was    formed into a polygonal shape having a diameter of 1 μm. The molded    inorganic particles were immersed in nickel plating solution, and    then the surface layer of the inorganic particle was coated with a    nickel layer. The inorganic particle coated with nickel was, as the    thermosetting resin, stirred in epoxy resin such that coagulation    was prevented. The filling factor was made to be 90%. Then, the    thermosetting resin was injected into a pot for potting such that    introduction of air was inhibited.-   (20) Potting was performed to insert the adhesive agent 75D into the    opening 571 (step (D) shown in FIG. 68). Then, heating was    performed, and then the projecting pin 576D made of covar was    placed. Then, hardening was performed at 200° C. so that joining was    performed. As a result, a package substrate was obtained (step (E)    shown in FIG. 68).    (Seventh Modification)

The basic structure was the same as that according to the firstmodification. As shown in FIG. 69 (A), nickel plating 572 was performedas the metal layer. Gold plating was not performed. As the projectingpin 576A, the inner portion was made of covar and the surface layer wasconstituted by gold plating. Thus, coating with gold was performed.

(Eighth Modification)

The basic structure was the same as that according to the firstmodification. As shown in FIG. 71 (E), the projecting pin 576E had astructure that the inner portion was made of ceramic 77, the surfacelayer was formed by nickel and copper coating. Thus, a package substratewas obtained.

(Ninth Modification)

Referring to FIGS. 72 and 73, a package substrate according to a ninthmodification will now be described.

In the ninth modification, a projecting pin 576F, the side surface andbottom surface of which were shown in FIG. 71 (F) is employed. Theprojecting pin 576F has five projections 576 b formed over the bottomsurface. Initially, an opening 571 is formed in the solder resist 571 ofa package substrate shown in FIG. 72 (A). Then, a recess 571 b allowedto communicate with a conductor circuit 658 is formed in the opening 571(FIG. 72 (B)). Then, a metal layer 73 made of nickel and so forth isformed in the opening 571 (FIG. 72 (C)). Then, an adhesive layer 575made of solder and so forth is formed on the metal layer 73 (FIG. 73(D)). Finally, the projecting pin 576F is accommodated in the opening571.

In the ninth modification, the electrical connection is established withthe conductor circuit 658 through the recess 571 b as well as theopening 571. Therefore, transmission of a large capacity electric powerand large capacity electric signal to the external substrate can beperformed without any problem.

(Tenth Modification)

The basic structure is the same as that according to the fifthembodiment. The solder layer was in the form of Sn/Sb.

COMPARATIVE EXAMPLE

The basic structure was the same as that according to the fifthembodiment. The electrode formed from the opening was molded as a solderball so that an IC chip was mounted.

The package substrates according to the fifth embodiment to the eighthmodification and the comparative example were evaluated such that thejoining strength, tensile test after the external substrate was mounted(the reliability test), occurrence of a crack and breakage of theelectrode were compared. Results were shown in the graph shown in FIG.74

The fifth embodiment to the eighth modification were such that thejoining strength was 20 Kg/cm² or greater, no defective connection ofthe electrode occurred in the tensile test and the reliability test wasresulted in no crack and breakage of the electrode under the heat cycleconditions after 1000 cycles.

Sixth Embodiment

A package substrate according to a sixth embodiment will now bedescribed with reference to FIG. 75.

The resin multilayer printed circuit board 10 has build-up circuitlayers 80U and 80D on the right and reverse sides of the core substrate30. The build-up circuit layers 80U and 80D incorporates a lower interlayer resin insulating layer 50 having a via hole 46, an upper interlayer resin insulating layer 60 having an upper via hole 66 and a solderresist layer 70 formed on the upper inter layer resin insulating layer60. A solder bump (an external connection terminal) 76 for establishingthe connection to an IC chip (not shown) is provided for the upper viahole 66 through an opening 71 of the solder resist 70. A conductiveconnecting pin (an external connection terminal) 78 for establishing theconnection to a daughter board (not shown) is connected to the lower viahole 66.

In the sixth embodiment, a through hole 36 for connecting the build-upcircuit layers 80U and 80D to each other penetrates the core substrate30 and the lower inter layer resin insulating layer 50. The through hole36 is filled with a resin filler 54. Cover plating 58 is applied to theopening. Similarly, the via hole 46 formed in the lower inter layerresin insulating layer 50 is filled with a resin filler 54. The openingis applied with cover plating 58.

In the sixth embodiment, a through hole is formed to penetrate the coresubstrate 30 and the lower inter layer resin insulating layer 50 bydrilling or a laser beam so that the through hole 36 is formed. The viahole 66 is formed immediately above the through hole 36. Therefore, thethrough hole 36 and the via hole 66 are disposed in line so that thelength of the electric line is shortened. Thus, a signal transmissionrate can be raised. Since the through hole 36 and the via hole 66 whichis connected to the external connection terminal (a solder pump 76 and aconductive connecting pin 78) are directly connected to each other,satisfactory connection reliability can be realized. In particular, thesixth embodiment has the structure that a filler 54 enclosed in thethrough hole 36 is flattened by grinding. Then, the cover plating (theconductor layer) 58 is applied. Then, the via hole 66 is formed on thecover plating 58. Therefore, the surface of the through hole 36 exhibitssatisfactory smoothness. Moreover, satisfactory connection reliabilitybetween the through hole 36 and the via hole 66 can be realized.

The multilayer printed circuit board according to the sixth embodimenthas the structure that the same filling resin 54 is enclosed in thethrough hole 36 and the lower via hole 46. The filler resin issimultaneously ground so as to be flattened. Therefore, the costreduction is permitted. The strength of the inside portion of thethrough hole and that in the via hole can uniformly be maintained. As aresult, the reliability of the multilayer printed circuit board can beimproved. The filler 54 enclosed in the via hole 46 is flattened bygrinding, and then the cover plating (the conductor layer) 58 forcovering the filler 54 is applied. Then, the upper via hole 66 is formedon the cover plating 58. Therefore, the surface of the lower via hole 46exhibits excellent flatness. Therefore, connection reliability betweenthe lower via hole 46 and the upper via hole 66 can be improved.

To secure the conductive connecting pin 78 to the lower via hole 66, asolder layer 77 in the form of Sn/Sb, Sn/Ag or Sn/Ag/Cu is provided.

1. A package substrate comprising: a core substrate; a conductive layerformed on the core substrate; an interlayer resin insulating layerincluding a filler comprising an inorganic compound, the interlayerresin insulating layer being formed on the core substrate and theconductive layer; a pad structure formed on the interlayer resininsulating layer, the pad structure comprising a via hole formed throughthe interlayer resin insulating layer and directly on the conductivelayer to electrically connect the pad structure to the conductive layer;a solder resist formed on the interlayer resin insulating layer and thepad structure, the solder resist having an opening exposing a partiallyexposed portion of the pad structure; and a conductive connecting pinconfigured to establish an electrical connection with another substrate,the conductive connecting pin being secured to the partially exposedportion of the pad structure via a solder, the solder being disposedover at least one metal layer formed in the partially exposed portion ofthe pad structure, wherein the at least one metal layer is formed in thepartially exposed portion of the pad structure after the opening isformed in the solder resist.
 2. The package substrate according to claim1, further comprising: at least one through-hole formed in the coresubstrate and having a through-hole conductor provided therein; and athrough-hole land formed on said core substrate as part of theconductive layer, the through-hole land being directly connected to thethrough-hole conductor.
 3. The package substrate according to claim 2,wherein the through-hole conductor comprises a plating layer formed on asidewall of the through-hole, and the through hole is filled with resinfiller.
 4. The package substrate according to claim 3, wherein thethrough-hole land comprises Ni alloy.
 5. The package substrate accordingto claim 2, wherein the via hole of the pad structure is directlyconnected to the through-hole land.
 6. The package substrate accordingto claim 5, wherein the via hole comprises a plurality of via holes eachbeing formed through the interlayer resin insulating layer and directlyon the through-hole land to electrically connect the respective via holeto the through-hole conductor.
 7. The package substrate according toclaim 6, wherein the plurality of via holes are formed on opposite sidesof the through-hole.
 8. The package substrate according to claim 1,further comprising a signal line formed on the interlayer resininsulating layer, wherein the signal line connects to the pad structure,and the signal line is covered with the solder resist.
 9. The packagesubstrate according to claim 1, wherein a diameter of the pad structureis 1.02 times to 100 times a diameter of the opening.
 10. The packagesubstrate according to claim 1, wherein the conductive connecting pincomprises a columnar connection portion and a plate-like securedportion, the secured portion is secured to the pad through the solder,and the conductive connecting pin comprises at least one of Cu, a copperalloy, Ti, Zn, Al and a noble metal.
 11. The package substrate accordingto claim 10, wherein the columnar connection portion has a constrictionportion having a diameter which is smaller than a diameter of anotherportion of the columnar connection portion.
 12. The package substrateaccording to claim 1, wherein the pad structure has a roughened surface.13. The package substrate according to claim 12, wherein the roughenedsurface comprises Ni alloy.
 14. The package substrate according to claim13, wherein the roughened surface comprises Cu-Ni-P.
 15. The packagesubstrate according to claim 1, wherein the at least one metal layerformed in the partially exposed portion of the pad structure comprises aplurality of metal layers.
 16. The package substrate according to claim1, wherein the at least one metal layer formed in the partially exposedportion of the pad structure comprises at least one metal which preventscorrosion.
 17. The package substrate according to claim 1, wherein theat least one metal layer formed in the partially exposed portion of thepad structure comprises at least one material selected from the groupconsisting of gold, silver, copper, nickel, tin, aluminum, lead,phosphorus, chrome, tungsten, molybdenum, titanium, platinum and solder.18. A package substrate comprising: a core substrate; a conductive layerformed on the core substrate; an interlayer resin insulating layerincluding a filler comprising an inorganic compound, the interlayerresin insulating layer being formed on the core substrate and theconductive layer; a pad structure formed on the interlayer resininsulating layer, the pad structure comprising a via hole formed throughthe interlayer resin insulating layer and directly on the conductivelayer to electrically connect the pad structure to the conductive layer;a solder resist formed on the interlayer resin insulating layer and thepad structure, the solder resist having an opening exposing a partiallyexposed portion of the pad structure; and conductive connecting meansfor establishing an electrical connection with another substrate, theconductive connecting means being secured to the partially exposedportion of the pad structure via solder, the solder being disposed overat least one metal layer formed in the partially exposed portion of thepad structure wherein the at least one metal layer is formed in thepartially exposed portion of the pad structure after the opening isformed in the solder resist.
 19. The package substrate according toclaim 18, wherein the at least one metal layer formed in the partiallyexposed portion of the pad structure comprises a plurality of metallayers.
 20. The package substrate according to claim 18, wherein the atleast one metal layer formed in the partially exposed portion of the padstructure comprises at least one metal which prevents corrosion.